Implementation of the external .net.dllexport configuration file

[3F]

Noticed earlier: #38 (comment)

<PropertyGroup Condition=" '$(DllExportIdent)' == '6C994FF1-7B8B-4B8F-B1EB-FC8B66EDF8B3' ">
  <DllExportNamespace>System.Runtime.InteropServices</DllExportNamespace>
  ...
</PropertyGroup>
<PropertyGroup Condition=" '$(DllExportIdent)' == '0415A0AA-76E4-43A4-BDC3-D115A6781C7D' ">
  <DllExportNamespace>net.r_eg.DllExport</DllExportNamespace>
  ...
</PropertyGroup>
<ItemGroup>
  <Reference Include="DllExport, Version=1.6.0.40687, Culture=neutral, PublicKeyToken=8337224c9ad9e356">
    <HintPath>..\packages\DllExport.1.6.0-beta2\gcache\metalib\DllExportClassLibrary1\DllExport.dll</HintPath>
    <Private>False</Private>
  </Reference>
</ItemGroup>
....

It helps to avoid reloading environment outside EnvDTE logic, and actually looks more flexible.

That is, user should to see finally .net.dllexport inside $(SolutionDir) and manage this via our manager or directly.

[3F]

• The default file name should be: .net.dllexport.targets
• location: Inside $(SolutionDir)
• Option to activate: Storage via $(wStorage)

<!-- Where to store configuration data. enum `CfgStorageType`. -->
<wStorage Condition="'$(wStorage)' == ''">Default</wStorage>

Sample:

<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <PropertyGroup Condition="'$(DllExportIdent)'=='56499BBA-E90A-4C99-B63B-B1A9FDB2DA6E'" Label="$(SolutionDir)DllExportClassLibrary1\DllExportClassLibrary1.csproj">
    <DllExportNamespace>System.Runtime.InteropServices</DllExportNamespace>
    <DllExportDDNSCecil>true</DllExportDDNSCecil>
    <PlatformTarget>x86</PlatformTarget>
    <DllExportOrdinalsBase>1</DllExportOrdinalsBase>
    <DllExportGenExpLib>true</DllExportGenExpLib>
    <DllExportOurILAsm>true</DllExportOurILAsm>
    <DllExportLeaveIntermediateFiles>false</DllExportLeaveIntermediateFiles>
    <DllExportTimeout>30000</DllExportTimeout>
  </PropertyGroup>
  <PropertyGroup Condition="'$(DllExportIdent)'=='D927DF2E-27A6-4970-B494-C8117CDCD6FB'" Label="$(SolutionDir)ClassLibrary2\ClassLibrary2.csproj">
    <DllExportNamespace>net.r_eg.DllExport</DllExportNamespace>
    <DllExportDDNSCecil>false</DllExportDDNSCecil>
    <PlatformTarget>x64</PlatformTarget>
    <DllExportOrdinalsBase>0</DllExportOrdinalsBase>
    <DllExportGenExpLib>false</DllExportGenExpLib>
    <DllExportOurILAsm>false</DllExportOurILAsm>
    <DllExportLeaveIntermediateFiles>true</DllExportLeaveIntermediateFiles>
    <DllExportTimeout>60000</DllExportTimeout>
    <DllExportSkipOnAnyCpu>false</DllExportSkipOnAnyCpu>
    <DllExportILAsmCustomPath>$(SolutionDir)bin\</DllExportILAsmCustomPath>
  </PropertyGroup>
  <ItemGroup>
    <Reference Include="DllExport, PublicKeyToken=8337224c9ad9e356">
      <HintPath>$(SolutionDir)packages\DllExport.1.6.0-beta2\gcache\metalib\$(DllExportNamespace)\$(DllExportMetaLibName)</HintPath>
      <Private>False</Private>
      <SpecificVersion>False</SpecificVersion>
    </Reference>
  </ItemGroup>
  <Import Project="$(SolutionDir)packages\DllExport.1.6.0-beta2\tools\net.r_eg.DllExport.targets" Condition="Exists('$(SolutionDir)packages\DllExport.1.6.0-beta2\tools\net.r_eg.DllExport.targets')" Label="8337224c9ad9e356" />
  <Target Name="DllExportRestorePkg" BeforeTargets="PrepareForBuild">
    <Warning Condition="!Exists('$(SolutionDir)DllExport.bat')" Text="We can't find 'DllExport.bat' in '$(SolutionDir)' - https://github.com/3F/DllExport" />
    <Exec Condition="('$(DllExportModImported)' != 'true' Or !Exists('$(SolutionDir)packages\DllExport.1.6.0-beta2\tools\net.r_eg.DllExport.targets')) And Exists('$(SolutionDir)DllExport.bat')" Command="cd &quot;$(SolutionDir)&quot; &amp; DllExport.bat -action Restore" />
  </Target>
</Project>