Item table progress; reorganized defines

Reorganized defines a bit; merged sound driver defines into other
defines as ram_map, split out definitions like ports.

Identified "color flash" variable where colors flashed on the screen are
stored. This is implemented by setting a color, setting the function to
execute after flash, and then letting the VBlank handler jump back to
the function after doing the flash.

Identified variable containing damage dealt to a monster.

Changed item table ring functions to ringequip functions; most of rings'
function is handled with equipment checks elsewhere.