Cache ascender/descender
Cache ascender/descender

Cache ascender/descender so they don't have to be queried every frame
for every glyph. This also makes it possible to more uniformly handle
drawings and glyphs.

ShiftMediaProject/libass,torque/libass,asimonov-im/libass,pigoz/libass-ct,libass/libass,pigoz/libass-ct,MrSmile/libass,sanyaade-g2g-repos/libass,torque/libass,Akemi/libass,astiob/libass,sanyaade-g2g-repos/libass,grigorig/libass,blinkseb/libass,rhlee/libass,ShiftMediaProject/libass,Akemi/libass,blinkseb/libass,MrSmile/libass,Akemi/libass,mwgoldsmith/libass,blinkseb/libass,xbmc/libass,mwgoldsmith/libass,stps/libass,stps/libass,sanyaade-g2g-repos/libass,richardpl/libass,tgoyne/libass,grigorig/libass,rhlee/libass,astiob/libass,pigoz/libass-ct,tgoyne/libass,asimonov-im/libass,Distrotech/libass,tgoyne/libass,Distrotech/libass,mwgoldsmith/libass,torque/libass,xbmc/libass,richardpl/libass,richardpl/libass,libass/libass,Distrotech/libass,rhlee/libass,stps/libass