Terminate drawings on {
Terminate drawings on {

This brings us in line with VSFilter
and also fixes Google Code issue #101.

Akemi/libass,Akemi/libass,libass/libass,astiob/libass,grigorig/libass,MrSmile/libass,stps/libass,Akemi/libass,MrSmile/libass,libass/libass,torque/libass,mwgoldsmith/libass,ShiftMediaProject/libass,pigoz/libass-ct,mwgoldsmith/libass,astiob/libass,mwgoldsmith/libass,xbmc/libass,grigorig/libass,stps/libass,ShiftMediaProject/libass,stps/libass,pigoz/libass-ct,xbmc/libass,pigoz/libass-ct,sanyaade-g2g-repos/libass,sanyaade-g2g-repos/libass,torque/libass,torque/libass,sanyaade-g2g-repos/libass