Wiki pages cruft cleanup


I cleaned up:

and removed a lot of cruft on these pages. The intention was:
- To separate the 'get involved' section from the the 'tips and tricks'-stuff a
  la: 'If you run Lattice C on AmigaOS, might get a faster build by applying a
  few drops of rose water to your keyboard'
- the 'get involved' pages are now short an sweet and not some overwhelming,
  messy and confusing page containing a lot of auxilary infos that are mostly
  irrelevant for a new starter:
  Please ensure to keep them that way.
- contact data is much more visible: IRC, mailing list, calls.

Please help keeping the wiki somewhat clean and do not overload the
introductionary pages with information only revelant in a subset of scenarios.