Consolidate Code of Conduct and technical guidelines

This merge request consolidates the Code of Conduct by splitting out the specific (technical) fora guidelines (moved back to the Wiki as "General guidelines"). The wiki article is linked to from a new "Further reading" section that explains its relation to the Terms of Service and the requirement of all users to review them before each use of any of the communication channels.

Additionally, the various subsections in the CoC are merged into more concise overarching sections (while largely leaving the wording intact).

The "Enforcement" section has been defined more clearly to point out more streamlined points of action.

Fixes #3 (closed)