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/routines/placegraphic.asm

@@ -0,0 +1,56 @@
+PlaceGraphic: ; 2ef6e
+; Fill wBoxAlignment-aligned box width b height c
+; with iterating tile starting from hGraphicStartTile at hl.
+; Predef $13
+
+	ld de, SCREEN_WIDTH
+
+	ld a, [wBoxAlignment]
+	and a
+	jr nz, .right
+
+	ld a, [hGraphicStartTile]
+.x1
+	push bc
+	push hl
+
+.y1
+	ld [hl], a
+	add hl, de
+	inc a
+	dec c
+	jr nz, .y1
+
+	pop hl
+	inc hl
+	pop bc
+	dec b
+	jr nz, .x1
+	ret
+
+.right
+; Right-aligned.
+	push bc
+	ld b, 0
+	dec c
+	add hl, bc
+	pop bc
+
+	ld a, [hGraphicStartTile]
+.x2
+	push bc
+	push hl
+
+.y2
+	ld [hl], a
+	add hl, de
+	inc a
+	dec c
+	jr nz, .y2
+
+	pop hl
+	dec hl
+	pop bc
+	dec b
+	jr nz, .x2
+	ret