build: open source Visual Studio extension

* moved SourcetrailPlugin to separate GitHub repository: https://github.com/CoatiSoftware/vs-sourcetrail
* changed Readme in ide_plugins folder to point to that repo and give instructions on how to install
* removed vsix from windows package
* renamed SourcetrailPlugin project to SourcetrailExtension
* changed assembly name to vs-sourcetrail
* removed plugin install script because the tests now use a configured experimental instance of Visual Studio
* added license file for cinder solution that is used in plugin integration tests
* replace license file with apache license
* added boilerplate notice of Apache License 2 to source files of plugin

.gitignore

@@ -22,13 +22,13 @@
 .idea
 .vscode
 
-/ide_plugins/vs/vs2015/SourcetrailPlugin/SourcetrailPlugin/bin
-/ide_plugins/vs/vs2015/SourcetrailPlugin/SourcetrailPlugin/obj
-/ide_plugins/vs/vs2015/SourcetrailPlugin/SourcetrailPluginTests/bin/Debug
-/ide_plugins/vs/vs2015/SourcetrailPlugin/SourcetrailPluginTests/bin/Release
-/ide_plugins/vs/vs2015/SourcetrailPlugin/SourcetrailPluginTests/obj
-/ide_plugins/vs/vs2015/SourcetrailPlugin/SourcetrailPluginUtility/bin
-/ide_plugins/vs/vs2015/SourcetrailPlugin/SourcetrailPluginUtility/obj
+/ide_plugins/vs/vs2015/SourcetrailPlugin/SourcetrailExtension/bin
+/ide_plugins/vs/vs2015/SourcetrailPlugin/SourcetrailExtension/obj
+/ide_plugins/vs/vs2015/SourcetrailPlugin/SourcetrailExtensionTests/bin/Debug
+/ide_plugins/vs/vs2015/SourcetrailPlugin/SourcetrailExtensionTests/bin/Release
+/ide_plugins/vs/vs2015/SourcetrailPlugin/SourcetrailExtensionTests/obj
+/ide_plugins/vs/vs2015/SourcetrailPlugin/SourcetrailExtensionUtility/bin
+/ide_plugins/vs/vs2015/SourcetrailPlugin/SourcetrailExtensionUtility/obj
 /ide_plugins/vs/vs2015/SourcetrailPlugin/VCProjectEngineWrapperInterfaces/bin
 /ide_plugins/vs/vs2015/SourcetrailPlugin/VCProjectEngineWrapperInterfaces/obj
 /ide_plugins/vs/vs2015/SourcetrailPlugin/VCProjectEngineWrapper/bin

ide_plugins/vs/README.md

@@ -0,0 +1,12 @@
+#vs-sourcetrail
+
+The Visual Studio extension source code is hosted at Github.
+
+The extension is available in the Visual Studio Marketplace. To install this extension follow these steps:
+* open Visual Studio
+* from the menu bar select `Tools` -> `Extensions and Updates...`
+* in the `Extensions and Updates` dialog choose `Online` -> `Visual Studio Gallery`
+* press `Ctrl` + `E` and enter "sourcetrail" into the search bar
+* click the install button
+
+Link to the repository: [vsce-sourcetrail](https://github.com/CoatiSoftware/vs-sourcetrail).