Use inline function to compute extra-short secondary names
Remove unused SW_* variables
Avoid some weapon name copying
Move demo ammo recording up so it works in immersion mode

Immersion mode bypasses draw_hud, so the calls to record ammo into the
demo were skipped.
Convert text index macros to ternary expressions
Use MENU_DIFFICULTY_TEXT for pause dialog
Remove unused gr_bm_ubitblt0x_rle parameter masked