screen/pgscreen: Use one thread for all pygame stuff.
screen/pgscreen: Improved keymap. Added colormap.
screen/modalscreen: Fix lua mode.

The ModeEvent must be posted before the lua code is executed.
Otherwise, mode switches won't work in lua mode.
screen/pgscreen: Add lua functions to handle windows.
screen/pgscreen: Add prompt mode display.
screen/pgscreen: Removed lua mode.

Lua mode will be generalized into prompt mode.
screen/pgscreen: Support for windows and multiple columns.
lua/mud/mg: Added binding for lua prompt.
colors: Added fg() to AString.