Defs : increased EXTREME_H from 4000 --> 32000
Weird shape generator : experiment with adding simple "prefabs" to the
initial map.  These are just rectangles atm.
test crud
Tweaked room-size parameters -- working well now.
Tweaked T_BRANCH_PROB again.
Hallway score tweak.
Weird shape generator : implemented ability to rotationally mirror the
generated map -- would be useful for making CTF maps.
Weird shape generator : add in a few squares (2x2 seeds in size), which
will be good for prefabs and stairwells.
brushlib : added xy_coord() utility for adding an X/Y coordinate.
Worked on adding shadow brushes in outdoor rooms.  [needs changes to CSG code...]