Fix remaining dangling sound pointer problems

Use IDs instead of pointers in s_sound

Use mobj_t pointers in s_sound instead of void pointers; I know that
degenmobj_t pointers get passed too, and I might switch the code over,
but boo type-punning in general; the real fix is to generalize the
functions in s_sound to take an ID and coordinate pointers... but not
right now.

Assign sector and line sound origins an ID

Start serializing sector and line sound origins

Remove outdated check in p_saveg

Remove some old doom_printf calls when INSTRUMENTED is defined