Organize the engine/ directory

This is an informed attempt at reorganizing the engine/ directory by
creating categorized subdirectories, in order to make it easier to
navigate and find things.

The directories created are as follows:
* engine/game: Contains all "minigames", things like the unown puzzle
and slot machine.
* engine/gfx: Contains all handling of graphics. From loading palettes
to playing animations.
* engine/link: Contains all multiplayer functionality.
* engine/menu: Contains all generic/misc. menus and menu code.
Other, more specialized menus are in their own subdirectories (pokedex,
pokegear, party menu, etc).
* engine/overworld: Contains all handling of the overworld. From loading
and connecting maps to wild encounters and the scripting engine.
* engine/pokegear: In the same vein as engine/pokedex, except it could
use some more splitting up.
* engine/pokemon: Contains everything related to manipulating pokemon
data. From the pokemon storage system to evolution and mail.
* engine/printer: Contains everything related to printing things as well
as the printer communication.
* engine/title: Contains intro sequences, title screens and credits.

engine/link/link_2.asm

@@ -0,0 +1,95 @@
+LinkMonStatsScreen: ; 4d319
+	ld a, [wMenuCursorY]
+	dec a
+	ld [wCurPartyMon], a
+	call LowVolume
+	predef StatsScreenInit
+	ld a, [wCurPartyMon]
+	inc a
+	ld [wMenuCursorY], a
+	call ClearScreen
+	call ClearBGPalettes
+	call MaxVolume
+	farcall LoadTradeScreenBorder
+	farcall Link_WaitBGMap
+	farcall InitTradeSpeciesList
+	farcall SetTradeRoomBGPals
+	call WaitBGMap2
+	ret
+
+Link_WaitBGMap: ; 4d354
+	call WaitBGMap
+	call WaitBGMap2
+	ret
+
+LinkTextbox2: ; 4d35b
+	ld h, d
+	ld l, e
+	push bc
+	push hl
+	call .PlaceBorder
+	pop hl
+	pop bc
+
+	ld de, wAttrMap - wTileMap
+	add hl, de
+	inc b
+	inc b
+	inc c
+	inc c
+	ld a, PAL_BG_TEXT
+.row
+	push bc
+	push hl
+.col
+	ld [hli], a
+	dec c
+	jr nz, .col
+	pop hl
+	ld de, SCREEN_WIDTH
+	add hl, de
+	pop bc
+	dec b
+	jr nz, .row
+	ret
+; 4d37e
+
+.PlaceBorder: ; 4d37e
+	push hl
+	ld a, $76
+	ld [hli], a
+	inc a
+	call .PlaceRow
+	inc a
+	ld [hl], a
+	pop hl
+	ld de, SCREEN_WIDTH
+	add hl, de
+.loop
+	push hl
+	ld a, "┌"
+	ld [hli], a
+	ld a, " "
+	call .PlaceRow
+	ld [hl], "─"
+	pop hl
+	ld de, SCREEN_WIDTH
+	add hl, de
+	dec b
+	jr nz, .loop
+
+	ld a, "┐"
+	ld [hli], a
+	ld a, "│"
+	call .PlaceRow
+	ld [hl], "└"
+	ret
+; 4d3ab
+
+.PlaceRow: ; 4d3ab
+	ld d, c
+.row_loop
+	ld [hli], a
+	dec d
+	jr nz, .row_loop
+	ret