Use weak-pointers in the font manager instead of ref-counting.
Use weak-pointers in the font manager instead of ref-counting.

This simplifies programming slightly, open fonts no longer need to be
closed when they're no longer used.

froggey/Mezzano,froggey/Mezzano,varjagg/Mezzano,AugustusHuang/Mezzano,varjagg/Mezzano,rvedam/Mezzano,AugustusHuang/Mezzano,rvedam/Mezzano