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.
first (quiet ugly) version of parallel log-reading for export