sync naming and file organisation conventions with HGSS

[red031000]

replace FUN_ with sub_
replace MOD with ov
change file structure to match HGSS (e.g. src and sub)
remove ARM_FUNC and THUMB_FUNC and replace with code16 and code32 like pokeheartgold has

all for a more consistent gen 4 decomp experience

[AsparagusEduardo]

change file structure to match HGSS (e.g. src and sub)

Is this the last remaining thing of this list?

[red031000]

that's the main one that hasn't been done yet

[red031000]

the rest I think have been