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.

# Conflicts:
#	constants/map_constants.asm
#	constants/wram_constants.asm
#	data/radio/oaks_pkmn_talk_routes.asm
#	data/radio/pnp_hidden_places.asm
#	engine/battle/core.asm
#	engine/breeding.asm
#	engine/phone/phone_scripts.asm
#	engine/radio.asm
#	maps/BattleTower1F.asm
#	maps/OlivineLighthouse2F.asm
#	maps/OlivineLighthouse6F.asm
#	maps/PokemonFanClub.asm
#	maps/RadioTower1F.asm
#	maps/RadioTower2F.asm
#	maps/Route30BerryHouse.asm
#	maps/Route34IlexForestGate.asm
#	maps/Route36NationalParkGate.asm
#	maps/RuinsOfAlphKabutoChamber.asm
#	maps/RuinsOfAlphResearchCenter.asm
#	maps/VermilionPort.asm
#	maps/VictoryRoad.asm

Since we're aiming for consistency across the codebase, I believe it
includes a uniform way to refer to the creatures this game consists of
in the labels of the code.
The only exceptions to this rule are labels referring to things named
through the use of the <PK><MN> or <PKMN> characters, in which case PKMN
is used.

Most of this was already consistent enough™, I just picked the
convention with the most occurences and fixed the outliers.

# Conflicts:
#	audio/engine.asm
#	constants/gfx_constants.asm
#	constants/map_data_constants.asm
#	constants/pokemon_data_constants.asm
#	constants/sprite_constants.asm
#	constants/wram_constants.asm
#	data/maps/data.asm
#	engine/battle/ai/scoring.asm
#	engine/battle/core.asm
#	engine/battle/effect_commands.asm
#	engine/battle/misc.asm
#	engine/battle_anims/getpokeballwobble.asm
#	engine/breeding.asm
#	engine/buy_sell_toss.asm
#	engine/decorations.asm
#	engine/events/battle_tower/battle_tower.asm
#	engine/events/battle_tower/rules.asm
#	engine/events/buena.asm
#	engine/events/bug_contest/contest_2.asm
#	engine/events/daycare.asm
#	engine/events/dratini.asm
#	engine/events/halloffame.asm
#	engine/events/happiness_egg.asm
#	engine/events/kurt.asm
#	engine/events/lucky_number.asm
#	engine/events/magnet_train.asm
#	engine/events/overworld.asm
#	engine/events/pokerus/pokerus.asm
#	engine/events/print_unown.asm
#	engine/events/print_unown_2.asm
#	engine/events/unown_walls.asm
#	engine/item_effects.asm
#	engine/link.asm
#	engine/mon_menu.asm
#	engine/player_object.asm
#	engine/routines/playslowcry.asm
#	engine/scripting.asm
#	engine/search.asm
#	engine/search2.asm
#	engine/specials.asm
#	engine/start_menu.asm
#	engine/timeset.asm
#	home/battle_vars.asm
#	home/map.asm
#	maps/GoldenrodUndergroundSwitchRoomEntrances.asm
#	maps/IlexForest.asm
#	maps/KrissHouse2F.asm
#	maps/Route39Barn.asm
#	mobile/mobile_12_2.asm
#	mobile/mobile_40.asm
#	mobile/mobile_5f.asm
#	wram.asm