Renamed a bunch of files, most of them one-off functions, to better fit
the general snake_case naming scheme. Also renamed some awfully long filenames.
Renamed `title` to `movies`.
Moved some functions from `engine/routines/` to their fitting
directories, and cleaned up the base `engine/` directory.
Moved `engine/pokemon/tmhm.asm` back to `engine/items/`.
Made a new subdirectory:
* engine/tilesets: Contains all map-related graphics routines.
