magic: import and decompile gesui, otsunami

[j3lee]

Two wave overlays, imported and fully decompiled (15 functions, no assembly left). One commit per overlay.

• gesui is Sewer Tsunami; otsunami is shared by Leviathan Scales, Big Wave and Huge Tidal Wave
• both draw the wave as a 20 by 16 grid of POLY_FT4 tiles whose height scrolls with the frame counter (GesuiWaveMeshTick, OtsunamiWaveMeshTick); gesui has two entries, the second mirrored
• stacked on psxsdk: add gte_avsz4 and gte_stotz to inline_c.h #320 (gte_avsz4 / gte_stotz): it includes that commit until that one is in

Each file opens with the attack it belongs to, in the form the other magic files use; an effect several attacks share lists them. Functions are named <Overlay><Thing><Verb> after what they draw or do; data keeps its D_ names.