FAS for MagicDraw Code

implemented the first half of "Update Associations between Activities" (ticket #4):
this is the synchronizing between containment and navigable aggregation associations.

created bidirectional hash map and eliminated some bugs. currently not working.

new development line for untested and/or not properly working implementation

As a basis for working on ticket 4: Added requirements for function 'update associations between activities' to the specification model

added draft guide "Introduction to MagicDraw Plugin Development"

Continued with MBDG'ed User Guide; xrefs and appendices added.

added MD model for model based document generation (MBDG) using the MBSE-Plugin

added FAS Tutorial to dist package (ticket #11)

Hide context menu entry when
- no project selected OR
- no node in containment tree selected OR
- no package selected