Organize the engine/ directory, take 2

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.

engine/pokemon/switchpartymons.asm

@@ -0,0 +1,145 @@
+_SwitchPartyMons:
+	ld a, [wd0e3]
+	dec a
+	ld [wBuffer3], a
+	ld b, a
+	ld a, [wMenuCursorY]
+	dec a
+	ld [wBuffer2], a
+	cp b
+	jr z, .skip
+	call .SwapMonAndMail
+	ld a, [wBuffer3]
+	call .ClearSprite
+	ld a, [wBuffer2]
+	call .ClearSprite
+.skip
+	ret
+
+.ClearSprite: ; 50f34 (14:4f34)
+	push af
+	hlcoord 0, 1
+	ld bc, 2 * SCREEN_WIDTH
+	call AddNTimes
+	ld bc, 2 * SCREEN_WIDTH
+	ld a, " "
+	call ByteFill
+	pop af
+	ld hl, wVirtualOAMSprite00
+	ld bc, 4 * SPRITEOAMSTRUCT_LENGTH
+	call AddNTimes
+	ld de, SPRITEOAMSTRUCT_LENGTH
+	ld c, 4
+.gfx_loop
+	ld [hl], SCREEN_WIDTH_PX ; y (off-screen)
+	add hl, de
+	dec c
+	jr nz, .gfx_loop
+	ld de, SFX_SWITCH_POKEMON
+	call WaitPlaySFX
+	ret
+
+.SwapMonAndMail: ; 50f62 (14:4f62)
+	push hl
+	push de
+	push bc
+	ld bc, wPartySpecies
+	ld a, [wBuffer2]
+	ld l, a
+	ld h, $0
+	add hl, bc
+	ld d, h
+	ld e, l
+	ld a, [wBuffer3]
+	ld l, a
+	ld h, $0
+	add hl, bc
+	ld a, [hl]
+	push af
+	ld a, [de]
+	ld [hl], a
+	pop af
+	ld [de], a
+	ld a, [wBuffer2]
+	ld hl, wPartyMon1Species
+	ld bc, PARTYMON_STRUCT_LENGTH
+	call AddNTimes
+	push hl
+	ld de, wd002
+	ld bc, PARTYMON_STRUCT_LENGTH
+	call CopyBytes
+	ld a, [wBuffer3]
+	ld hl, wPartyMon1
+	ld bc, PARTYMON_STRUCT_LENGTH
+	call AddNTimes
+	pop de
+	push hl
+	ld bc, PARTYMON_STRUCT_LENGTH
+	call CopyBytes
+	pop de
+	ld hl, wd002
+	ld bc, PARTYMON_STRUCT_LENGTH
+	call CopyBytes
+	ld a, [wBuffer2]
+	ld hl, wPartyMonOT
+	call SkipNames
+	push hl
+	call .CopyNameTowd002
+	ld a, [wBuffer3]
+	ld hl, wPartyMonOT
+	call SkipNames
+	pop de
+	push hl
+	call .CopyName
+	pop de
+	ld hl, wd002
+	call .CopyName
+	ld hl, wPartyMonNicknames
+	ld a, [wBuffer2]
+	call SkipNames
+	push hl
+	call .CopyNameTowd002
+	ld hl, wPartyMonNicknames
+	ld a, [wBuffer3]
+	call SkipNames
+	pop de
+	push hl
+	call .CopyName
+	pop de
+	ld hl, wd002
+	call .CopyName
+	ld hl, sPartyMail
+	ld a, [wBuffer2]
+	ld bc, MAIL_STRUCT_LENGTH
+	call AddNTimes
+	push hl
+	ld de, wd002
+	ld bc, MAIL_STRUCT_LENGTH
+	ld a, BANK(sPartyMail)
+	call GetSRAMBank
+	call CopyBytes
+	ld hl, sPartyMail
+	ld a, [wBuffer3]
+	ld bc, MAIL_STRUCT_LENGTH
+	call AddNTimes
+	pop de
+	push hl
+	ld bc, MAIL_STRUCT_LENGTH
+	call CopyBytes
+	pop de
+	ld hl, wd002
+	ld bc, MAIL_STRUCT_LENGTH
+	call CopyBytes
+	call CloseSRAM
+	pop bc
+	pop de
+	pop hl
+	ret
+
+.CopyNameTowd002: ; 51036 (14:5036)
+	ld de, wd002
+
+.CopyName: ; 51039 (14:5039)
+	ld bc, NAME_LENGTH
+	call CopyBytes
+	ret