Sync Makefile and tools with pokeemerald

Includes a few significant changes, alongside numerous smaller fixes to the tools and Makefile:

Support for enums in assembly (https://github.com/pret/pokeemerald/pull/1984)
Correctly generate map_groups.h and layouts.h before they're needed (https://github.com/pret/pokeemerald/pull/1949)
Scaninc speed improvements (https://github.com/pret/pokeemerald/pull/1954)
Makefile reorganization (https://github.com/pret/pokeemerald/pull/1950)
Generate build files from .mid with a .cfg file instead of explicit make rules (https://github.com/pret/pokeemerald/pull/1957)
Improve error messages for missing dependencies (https://github.com/pret/pokeemerald/pull/2031)

pret / pokefirered