Adds Post-Processing feature. Related issue #144 (#148)

* MvsSln up to rev `9c39498` due to 3F/MvsSln#25

Part of #144

* Post-Processing #148: Implemented backend logic with configurable environment:

Format: $(SolutionPath);$(MSBuildThisFileFullPath);...populated property names...;....

```
<Target Name="DllExportPostProc">

    <!-- Now we can access the following properties and items:

    $(DllExport)     - version
    $(DllExportSln)  - full path to .sln which controls current project
    $(DllExportPrj)  - full path to current project where processed .NET DllExport

    @(DllExportDirX64)    - $(TargetDir)x64\*.*
    @(DllExportDirX86)    - $(TargetDir)x86\*.*
    @(DllExportDirBefore) - $(TargetDir)Before\*.*
    @(DllExportDirAfter)  - $(TargetDir)After\*.*

    @(DllExportDependents + populated property name)
       - each populated properties from DllExportInvokedPoint, e.g. DllExportDependentsTargetDir

    @(DllExportDependencies + populated property name)
      - each populated properties from DllExportInvokedPoint, e.g. DllExportDependenciesTargetDir

    -->

</Target>
```

* Post-Proc. Added support of external .net.dllexport.targets

* PostProc usage has been moved into ExportTaskImplementation

* Fixed MSB4094 when using the same properties

+Checking the existence of our entry point

* `DllExportInvokedPoint` renamed as `DllExportProcEnv`

* Basic GUI support for predefined options in Post-Proc feature

That is,

*! Some Post-Proc features are not yet available in GUI. But you can already configure it with msbuild.

* cleanup

* Updated data in SimpleConfFormater.Parse()

+PostProc +PreProc

* MvsSln up to rev `838fab00dd` /? #148 (comment)

* MvsSln up to rev `e07c5806dd`: +`ProjectReference` support without obsolete projectguid

* Updated MvsSln 2.5.2

* Added multiple destination support via derivative targets:
#148 (comment)

* +`DllExportSeqDependents...` Includes sequential referencing through other projects

RGiesecke.DllExport.MSBuild/AssemblyInfo.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Reflection;
+using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using net.r_eg.DllExport;
 
@@ -11,3 +12,12 @@
 [assembly: ComVisible(false)]
 
 [assembly: AssemblyVersion(DllExportVersion.S_NUM_REV)]
+
+[assembly: InternalsVisibleTo
+(
+    "net.r_eg.DllExport.Wizard, PublicKey=00240000048000009400000006020000002400005253413100040000010001002ff3c0078e6021" +
+                                        "1fd2f8fece1d935ad41c19ed43fd19cc7ef2b397b328d6f9bb391e7f16db5927614aff97f837fa" +
+                                        "fa455d8c42701cdcc0f67fc897355a03c0bec67b69c0c5dfb627409d647a5dad09751e4dd6a907" +
+                                        "e74b5b07ebd25bd5a62cbcddd6286d8726d6111d8feecd8101d2d681d0e004c0697065d07ba5a5" +
+                                        "cce179a4"
+)]

RGiesecke.DllExport.MSBuild/Executor.cs

@@ -0,0 +1,95 @@
+//# Author of original code ([Decompiled] MIT-License): Copyright (c) 2009-2015  Robert Giesecke
+//# Use Readme & LICENSE files for details.
+
+//# Modifications: Copyright (c) 2016-2020  Denis Kuzmin < x-3F@outlook.com > GitHub/3F
+//$ Distributed under the MIT License (MIT)
+
+using System;
+using System.Collections.Generic;
+using Microsoft.Build.Execution;
+using Microsoft.Build.Framework;
+using Microsoft.Build.Utilities;
+using net.r_eg.DllExport;
+using net.r_eg.MvsSln.Core;
+
+namespace RGiesecke.DllExport.MSBuild
+{
+    internal class Executor: IPostProcExecutor
+    {
+        private readonly TaskLoggingHelper log;
+
+        /// <summary>
+        /// Executes IXProject through MSBuild engine.
+        /// </summary>
+        /// <param name="xp"></param>
+        /// <param name="entrypoint">Initial target.</param>
+        /// <param name="properties">Additional properties that will be available when executing code.</param>
+        /// <returns>True if request was a complete success.</returns>
+        public bool Execute(IXProject xp, string entrypoint, IDictionary<string, string> properties = null)
+        {
+            if(xp == null) {
+                throw new ArgumentNullException(nameof(xp));
+            }
+
+            UpdateGlobalProperties(xp, properties);
+
+            var request = new BuildRequestData
+            (
+                xp.Project.CreateProjectInstance(),
+                new string[] { entrypoint ?? throw new ArgumentNullException(nameof(entrypoint)) }, 
+                new HostServices()
+            );
+
+#if !NET40
+
+            using(BuildManager manager = new BuildManager(DllExportVersion.DXP)) {
+                return Build(manager, request, false);
+            }
+
+#else
+
+            // 4.0.30319
+            return Build(new BuildManager(DllExportVersion.DXP), request, false);
+
+#endif
+        }
+
+        public Executor(TaskLoggingHelper log)
+        {
+            this.log = log ?? throw new ArgumentNullException(nameof(log));
+        }
+
+        protected bool Build(BuildManager manager, BuildRequestData request, bool silent)
+        {
+            BuildResult result = manager.Build
+            (
+                new BuildParameters()
+                {
+                    MaxNodeCount = 4,
+                    Loggers = new List<ILogger>() 
+                    {
+                        new ExecutorLogger(log) {
+                            Verbosity = silent ? LoggerVerbosity.Quiet : LoggerVerbosity.Normal
+                        }
+                    }
+                },
+                request
+            );
+
+            return result.OverallResult == BuildResultCode.Success;
+        }
+
+        private void UpdateGlobalProperties(IXProject xp, IDictionary<string, string> properties)
+        {
+            if(properties == null) {
+                return;
+            }
+
+            foreach(var prop in properties) 
+            {
+                xp.Project.SetGlobalProperty(prop.Key, prop.Value);
+                log.LogMessage(MessageImportance.Low, Resources._0_is_configured_as_1, prop.Key, prop.Value);
+            }
+        }
+    }
+}

RGiesecke.DllExport.MSBuild/ExecutorLogger.cs

@@ -0,0 +1,38 @@
+//# Author of original code ([Decompiled] MIT-License): Copyright (c) 2009-2015  Robert Giesecke
+//# Use Readme & LICENSE files for details.
+
+//# Modifications: Copyright (c) 2016-2020  Denis Kuzmin < x-3F@outlook.com > GitHub/3F
+//$ Distributed under the MIT License (MIT)
+
+using System;
+using Microsoft.Build.Framework;
+using Microsoft.Build.Utilities;
+
+namespace RGiesecke.DllExport.MSBuild
+{
+    internal class ExecutorLogger: ILogger
+    {
+        private readonly TaskLoggingHelper log;
+
+        public string Parameters { get; set; }
+
+        public LoggerVerbosity Verbosity { get; set; }
+
+        public void Shutdown()
+        {
+
+        }
+
+        public void Initialize(IEventSource eventSource)
+        {
+            eventSource.WarningRaised   += (sender, e) => log.LogWarning($"[{e.LineNumber}]: {e.Code} - '{e.Message}'");
+            eventSource.ErrorRaised     += (sender, e) => log.LogError($"[{e.LineNumber}]: {e.Code} - '{e.Message}'");
+
+            if(Verbosity != LoggerVerbosity.Quiet) {
+                eventSource.AnyEventRaised += (sender, e) => log.LogMessage(MessageImportance.Low, $"{nameof(ExecutorLogger)}: {e.Message}");
+            }
+        }
+
+        public ExecutorLogger(TaskLoggingHelper log) => this.log = log ?? throw new ArgumentNullException(nameof(log));
+    }
+}

RGiesecke.DllExport.MSBuild/IPostProcExecutor.cs

@@ -0,0 +1,23 @@
+//# Author of original code ([Decompiled] MIT-License): Copyright (c) 2009-2015  Robert Giesecke
+//# Use Readme & LICENSE files for details.
+
+//# Modifications: Copyright (c) 2016-2020  Denis Kuzmin < x-3F@outlook.com > GitHub/3F
+//$ Distributed under the MIT License (MIT)
+
+using System.Collections.Generic;
+using net.r_eg.MvsSln.Core;
+
+namespace RGiesecke.DllExport.MSBuild
+{
+    internal interface IPostProcExecutor
+    {
+        /// <summary>
+        /// Executes IXProject through MSBuild engine.
+        /// </summary>
+        /// <param name="xp"></param>
+        /// <param name="entrypoint">Initial target.</param>
+        /// <param name="properties">Additional properties that will be available when executing code.</param>
+        /// <returns>True if request was a complete success.</returns>
+        bool Execute(IXProject xp, string entrypoint, IDictionary<string, string> properties = null);
+    }
+}