RakudoBrew: Added completion for switch command.

Also added some more 'versions' for build command. Idealy all known
versions will be resolved on tabpress via rakudobrew's clone of rakudo.
Padre: Added basic padre support.
Added  info about panda Module Completion

Moduulecompletion requires a projects.json in inst path.
users using system installations of perl6 and panda will probably
not have any problems, but those with home-dir and rakudobrew
installations (especialy with multiple versions) will need to run
panda update
at once per panda/perl6 upgrade/newversionswitch