Version 1.0

• #17 Add Exec provider that executes an executable and provides its output.
• #18 Add conditional providers under sub-namespaces String, Int and Bool:
  IF, EQ, NE, GT, GE, LT, LE, AND, OR, XOR, NOT.
• #19 Try to parse string values as int or bool, and provide *AsInt / *AsBool values on success.

Version 0.4

• #2 TextFile: Add ``..`` to access the parent directory.
• TextFile: Add optional parameter Encoding.
  The possible values are UTF-8, UTF-16-le, UTF-16-be, UTF-32-le and UTF-32-be.
  When not provided, the encoding is guessed automatically, as before.
• #12 TextFile: Strip the byte order mark from text content.
• #14 Env and TextFile: Add optional parameter EnsureExists.
  When true, if the file or environment variable doesn't exist, a compile-time error is raised.
  Otherwise, DefaultValue is used, or an empty string if not provided, as before.

Version 0.3

• Env: Add ability to load .env file from resolution path.
  Add LoadEnvFile: bool static parameter to decide whether to load the .env file.

Version 0.2.7

• Add assemblies to the NuGet package whose presence is required to build a netstandard2.0 library while running the compiler on net4x.
• Add net45 version of the library for compatibility with pre-netstandard2.0 frameworks.

Version 0.2

• Remove EnvOrDefault and move it to Env
• Remove TextFileOrDefault and move it to TextFile
• Add BuildDate<?format> provider

Version 0.1

• Env provider
• EnvOrDefault<name, ?default> provider
• TextFile provider
• TextFileOrDefault<path, ?default> provider