Match System.Reactive namespaces

This makes RxFree a 100% compatible drop-in replacement if only the provided types are used in a given project. Likewise, if the need arises for feature not provided in RxFree, it's trivial to "migrate" to System.Reactive: just uninstall RxFree and install System.Reactive and start using whatever is missing from this project.

Fixes #9

src/RxFree.Tests/DisposableTests.cs

@@ -1,4 +1,4 @@
-using System;
+using System.Reactive.Disposables;
 using Xunit;
 
 namespace RxFree.Tests

src/RxFree.Tests/LinqTests.cs

@@ -1,5 +1,6 @@
-using System;
-using System.Linq;
+using System.Linq;
+using System.Reactive.Linq;
+using System.Reactive.Subjects;
 using Xunit;
 
 namespace System

src/RxFree.Tests/SubjectTests.cs

@@ -1,4 +1,4 @@
-using System.Linq;
+using System.Reactive.Subjects;
 using Xunit;
 
 namespace System

src/RxFree/build/Legacy/AnonymousObserver.cs

@@ -1,6 +1,6 @@
 using System.Runtime.ExceptionServices;
 
-namespace System
+namespace System.Reactive
 {
     /// <summary>
     /// Create an <see cref="IObserver{T}"/> instance from delegate-based implementations 

src/RxFree/build/Legacy/CompositeDisposable.cs

@@ -5,7 +5,7 @@
 using System.Runtime.CompilerServices;
 using System.Threading;
 
-namespace System
+namespace System.Reactive.Disposables
 {
     /// <summary>
     /// Represents a group of disposable resources that are disposed together.

src/RxFree/build/Legacy/Disposable.cs

@@ -2,7 +2,7 @@
 using System.Diagnostics.CodeAnalysis;
 using System.Threading;
 
-namespace System
+namespace System.Reactive.Disposables
 {
     /// <summary>
     /// Provides a set of static methods for creating <see cref="IDisposable"/> objects.

src/RxFree/build/Legacy/ObservableExtensions.OfType.cs

@@ -1,6 +1,8 @@
-namespace System
+using System.Reactive.Subjects;
+
+namespace System.Reactive.Linq
 {
-    partial class ObservableExtensions
+    static partial class ObservableExtensions
     {
         /// <summary>
         /// Filters the elements of an observable sequence based on the specified type.

src/RxFree/build/Legacy/ObservableExtensions.Select.cs

@@ -1,4 +1,6 @@
-namespace System
+using System.Reactive.Subjects;
+
+namespace System.Reactive.Linq
 {
     partial class ObservableExtensions
     {

src/RxFree/build/Legacy/ObservableExtensions.Where.cs

@@ -1,4 +1,6 @@
-namespace System
+using System.Reactive.Subjects;
+
+namespace System.Reactive.Linq
 {
     partial class ObservableExtensions
     {

src/RxFree/build/Legacy/ObservableExtensions.cs

@@ -1,6 +1,7 @@
 // <auto-generated />
 using System.CodeDom.Compiler;
 using System.Diagnostics.CodeAnalysis;
+using System.Reactive;
 using System.Runtime.CompilerServices;
 using System.Runtime.ExceptionServices;
 

src/RxFree/build/Legacy/StableCompositeDisposable.cs

@@ -2,7 +2,7 @@
 using System.ComponentModel;
 using System.Diagnostics.CodeAnalysis;
 
-namespace System
+namespace System.Reactive.Disposables
 {
     /// <summary>
     /// For compatibility with Rx

src/RxFree/build/Legacy/Subject.cs

@@ -10,7 +10,7 @@
 using System.Runtime.CompilerServices;
 using System.Threading;
 
-namespace System
+namespace System.Reactive.Subjects
 {
     /// <summary>
     /// Represents an object that is both an observable sequence as well as an observer.

src/RxFree/build/NotNull/AnonymousObserver.cs

@@ -1,6 +1,6 @@
 using System.Runtime.ExceptionServices;
 
-namespace System
+namespace System.Reactive
 {
     /// <summary>
     /// Create an <see cref="IObserver{T}"/> instance from delegate-based implementations 

src/RxFree/build/NotNull/CompositeDisposable.cs

@@ -6,7 +6,7 @@
 using System.Runtime.CompilerServices;
 using System.Threading;
 
-namespace System
+namespace System.Reactive.Disposables
 {
     /// <summary>
     /// Represents a group of disposable resources that are disposed together.

src/RxFree/build/NotNull/Disposable.cs

@@ -3,7 +3,7 @@
 using System.Diagnostics.CodeAnalysis;
 using System.Threading;
 
-namespace System
+namespace System.Reactive.Disposables
 {
     /// <summary>
     /// Provides a set of static methods for creating <see cref="IDisposable"/> objects.

src/RxFree/build/NotNull/ObservableExtensions.OfType.cs

@@ -1,6 +1,8 @@
-namespace System
+using System.Reactive.Subjects;
+
+namespace System.Reactive.Linq
 {
-    partial class ObservableExtensions
+    static partial class ObservableExtensions
     {
         /// <summary>
         /// Filters the elements of an observable sequence based on the specified type.

src/RxFree/build/NotNull/ObservableExtensions.Select.cs

@@ -1,4 +1,6 @@
-namespace System
+using System.Reactive.Subjects;
+
+namespace System.Reactive.Linq
 {
     partial class ObservableExtensions
     {

src/RxFree/build/NotNull/ObservableExtensions.Where.cs

@@ -1,4 +1,6 @@
-namespace System
+using System.Reactive.Subjects;
+
+namespace System.Reactive.Linq
 {
     partial class ObservableExtensions
     {

src/RxFree/build/NotNull/ObservableExtensions.cs

@@ -2,6 +2,7 @@
 #nullable enable
 using System.CodeDom.Compiler;
 using System.Diagnostics.CodeAnalysis;
+using System.Reactive;
 using System.Runtime.CompilerServices;
 using System.Runtime.ExceptionServices;
 

src/RxFree/build/NotNull/StableCompositeDisposable.cs

@@ -3,7 +3,7 @@
 using System.ComponentModel;
 using System.Diagnostics.CodeAnalysis;
 
-namespace System
+namespace System.Reactive.Disposables
 {
     /// <summary>
     /// For compatibility with Rx

src/RxFree/build/NotNull/Subject.cs

@@ -11,7 +11,7 @@
 using System.Runtime.CompilerServices;
 using System.Threading;
 
-namespace System
+namespace System.Reactive.Subjects
 {
     /// <summary>
     /// Represents an object that is both an observable sequence as well as an observer.

src/RxFree/build/Nullable/AnonymousObserver.cs

@@ -1,6 +1,6 @@
 using System.Runtime.ExceptionServices;
 
-namespace System
+namespace System.Reactive
 {
     /// <summary>
     /// Create an <see cref="IObserver{T}"/> instance from delegate-based implementations 

src/RxFree/build/Nullable/CompositeDisposable.cs

@@ -6,7 +6,7 @@
 using System.Runtime.CompilerServices;
 using System.Threading;
 
-namespace System
+namespace System.Reactive.Disposables
 {
     /// <summary>
     /// Represents a group of disposable resources that are disposed together.

src/RxFree/build/Nullable/Disposable.cs

@@ -3,7 +3,7 @@
 using System.Diagnostics.CodeAnalysis;
 using System.Threading;
 
-namespace System
+namespace System.Reactive.Disposables
 {
     /// <summary>
     /// Provides a set of static methods for creating <see cref="IDisposable"/> objects.

src/RxFree/build/Nullable/ObservableExtensions.OfType.cs

@@ -1,6 +1,8 @@
-namespace System
+using System.Reactive.Subjects;
+
+namespace System.Reactive.Linq
 {
-    partial class ObservableExtensions
+    static partial class ObservableExtensions
     {
         /// <summary>
         /// Filters the elements of an observable sequence based on the specified type.

src/RxFree/build/Nullable/ObservableExtensions.Select.cs

@@ -1,4 +1,6 @@
-namespace System
+using System.Reactive.Subjects;
+
+namespace System.Reactive.Linq
 {
     partial class ObservableExtensions
     {

src/RxFree/build/Nullable/ObservableExtensions.Where.cs

@@ -1,4 +1,6 @@
-namespace System
+using System.Reactive.Subjects;
+
+namespace System.Reactive.Linq
 {
     partial class ObservableExtensions
     {

src/RxFree/build/Nullable/ObservableExtensions.cs

@@ -2,6 +2,7 @@
 #nullable enable
 using System.CodeDom.Compiler;
 using System.Diagnostics.CodeAnalysis;
+using System.Reactive;
 using System.Runtime.CompilerServices;
 using System.Runtime.ExceptionServices;
 

src/RxFree/build/Nullable/StableCompositeDisposable.cs

@@ -3,7 +3,7 @@
 using System.ComponentModel;
 using System.Diagnostics.CodeAnalysis;
 
-namespace System
+namespace System.Reactive.Disposables
 {
     /// <summary>
     /// For compatibility with Rx

src/RxFree/build/Nullable/Subject.cs

@@ -11,7 +11,7 @@
 using System.Runtime.CompilerServices;
 using System.Threading;
 
-namespace System
+namespace System.Reactive.Subjects
 {
     /// <summary>
     /// Represents an object that is both an observable sequence as well as an observer.