Add some checks to prevent loading invalid numbers of sectors and lines

Fix crash loading a new map with sound disabled

Break debugging options out separately; goodbye PRBOOM_DEBUG

Switch screen wipe PRNG to non-sync-critical

Add D_RandomRange function; D_Random returns a huge range and is
therefore slow.

Only make the PRNG changes in s_sound and f_wipe in DELTASYNC mode;
otherwise demos will desync