I have no idea why this was a thing (do people store this repo on FAT32
flash drives or something?), but quite a bit of files had a permission
of 755. This isn't really a problem, but it's inconsistent and weird.
Renamed `game` to `games` and `menu` to `menus`.
Moved some functions from `engine/routines/` to their fitting subdirectories.
Made two new subdirectories:
* engine/rtc: Contains all RTC-related things. Menus, hardware, misc
functions.
* engine/items: Contains all item-related things. Pack, item effects,
other item handlers.
