Fixed|Ring Zero: Fold title should say "(0)" when no games in the subset

The 'noGames' indicator was counted as a child inside the subset.
Builder|Pilot: Source packaging task

Only the "trusty" builder is now responsible for source packaging
and the Launchpad PPA upload. "saucy" is obsolete and the VM is gone.
Refactor|Cleanup|libdoomsday: Added base class for definition records

Various types of definitions have a number of common methods, such as
order(), so having a base class for the accessors is appropriate.
libdoomsday: Improved documentation
Merge branch 'master' into gl2-models