Add font characters for '/' and '?', needed by some text strings.
Adjust the vertical height of the ':' character, and remove some
leftover menu graphics that are no longer needed.
Some source ports (PrBoom, Eternity Engine, etc.) come with their own
PWAD files that include custom text graphic lumps for extended menus.
Include some overrides in Freedoom for common ones, so that when
playing in these ports the menus have a consistent look and feel.
Remove the big text graphic images used for the menus and the
intermission screen. Instead, generate these graphics programatically
from a script. This allows them to be easily changed and extended
as desired.
