implemented Quake-compatible savegame saving (writes 64 or more styles)

implemented Quake-compatible savegame saving (writes 64 or more styles)
enhanced savegame format with a large comment block at the end
containing the true lightstyle data (not padded with m lines), and model
and sound precaches, this should fix the famous Quake bug of reloading a
savegame with a different version of a mod, or a mod that randomly
precaches different monsters or similar

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@8521 d7cf8633-e32d-0410-b094-e92efae38249