Remove all code from main.asm (some labeled INCBINs, like out-of-context graphics, are still present)

engine/routines/ stores isolated out-of-context routines as individual files. It might be preferable later to append them to their related engine/ files in unique little SECTIONs, relying on the linkerscript to place them appropriately; or some other organization method. In the meantime, they're now easily findable apart from main.asm's other content.

engine/link_2.asm

@@ -0,0 +1,91 @@
+LinkMonStatsScreen: ; 4d319
+	ld a, [wMenuCursorY]
+	dec a
+	ld [CurPartyMon], a
+	call LowVolume
+	predef StatsScreenInit
+	ld a, [CurPartyMon]
+	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, AttrMap - TileMap
+	add hl, de
+	inc b
+	inc b
+	inc c
+	inc c
+	ld a, $7
+.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
+
+.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
+
+.PlaceRow: ; 4d3ab
+	ld d, c
+.row_loop
+	ld [hli], a
+	dec d
+	jr nz, .row_loop
+	ret