logic: update Visual Studio plugin to support Visual Studio 2017

* changed description text of Visual Studio plugin
* changed plugin install targets to include VS 2017
* add license file with MIT license
* updated vsix for deployment

* implement wrapper for all used classes of VCProjectEngine.dll since you cannot just use the oldest version of this
  assembly (see https://stackoverflow.com/questions/44288050/typecast-fails-when-visual-studio-extension-uses-reference-to-older-assembly).
* improved serialization and deserialization of compile commands and compilation databases.
* updated used JSON package
* rename CommandObject to CompileCommand
* changed implementation to keep non-existent file paths in cdb
* made methods of SolutionParser non-static
* replace spaces with tabs

* added IntegrationTests project
* configured tests to simulate a new instance of VisualStudio
* added cinder as test project for integration tests
* remove all absolute paths from expected output of integration tests

fortune cookie message = A stranger will bring great meaning to your life.

ide_plugins/vs/vs2015/SourcetrailPlugin/VCProjectEngineWrapper/VCCLCompilerToolWrapper.cs

@@ -0,0 +1,70 @@
+using Microsoft.VisualStudio.VCProjectEngine;
+
+namespace VCProjectEngineWrapper
+{
+	public class
+#if (VS2012)
+		VCCLCompilerToolWrapperVs2012
+#elif (VS2013)
+		VCCLCompilerToolWrapperVs2013
+#elif (VS2015)
+		VCCLCompilerToolWrapperVs2015
+#elif (VS2017)
+		VCCLCompilerToolWrapperVs2017
+#endif
+		: IVCCLCompilerToolWrapper
+	{
+		private VCCLCompilerTool _wrapped = null;
+
+		public
+#if (VS2012)
+			VCCLCompilerToolWrapperVs2012
+#elif (VS2013)
+			VCCLCompilerToolWrapperVs2013
+#elif (VS2015)
+			VCCLCompilerToolWrapperVs2015
+#elif (VS2017)
+			VCCLCompilerToolWrapperVs2017
+#endif
+			(object wrapped)
+		{
+			_wrapped = wrapped as VCCLCompilerTool;
+		}
+
+		public bool isValid()
+		{
+			return (_wrapped != null);
+		}
+
+		public string GetWrappedVersion()
+		{
+			return Utility.GetWrappedVersion();
+		}
+
+		public string GetAdditionalOptions()
+		{
+			return _wrapped.AdditionalOptions;
+		}
+
+		public bool GetCompilesAsC()
+		{
+			return _wrapped.CompileAs == CompileAsOptions.compileAsC;
+		}
+
+		public string GetToolPath()
+		{
+			return _wrapped.ToolPath;
+		}
+
+		public string[] GetAdditionalIncludeDirectories()
+		{
+			return _wrapped.AdditionalIncludeDirectories.Split(';');
+		}
+
+		public string[] GetPreprocessorDefinitions()
+		{
+			return _wrapped.PreprocessorDefinitions.Split(';');
+		}
+
+	}
+}