doc: remove obsolete GAPDoc comments

Instead, add comments which point to the actual documentation.
doc: rewrap documentation strings, first step towards readability
doc: fix some typos in the manual
doc: Change mentions of CreateAutoDoc to CreateAutomaticDocumentation
doc: more cleanup
doc: major overhaul of the documentation

This removes most of the repetition in the manual, which makes maintenance
easier, and also helps user who now have a much easier time to spot the
differences between the various AutoDoc functions.

The readability of both the documentation source as well as of the
generated manual is also improved.
doc: move Declare* funcs into separate section
doc: regenerate documentation