Introduced R# environment to access extension data.

The plug-in/extension id is now centrally defined as a constant in the R# environment. Furthermore, there's a central component that retrieves our R# extension in the production environment and returns a dummy in the development environment.
generation of Install- and UpdateEvents added
review of PluginVersionChangeObserver
Replaced tmp RSEnv by real implementation.
* track only visible windows
* add tests for new feature
Reviewed tracking of visible windows for IDE-state events.
Added missing interface to RSEnv.
Fixed project file.
Updated local build script.
implemented Analysis to fulfil several tests regarding declarations and assignments
extended Analysis to include further assignments and first invocation
extended Analysis to incluse further simple invocations
Analysis: composed invocations
Analysis: call-chains
updated tests according to todays review
introduced context to the visitors
moved transformer and utils to sub-folders
Analysis: control structures
fixes after rebase && Analysis: while- & do-loop
Refactorings + Analysis: static-invoke, this-invoke, base-invoke