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/drawkrispackgfx.asm

@@ -0,0 +1,20 @@
+DrawKrisPackGFX: ; 48e81
+	ld hl, PackFGFXPointers
+	add hl, de
+	add hl, de
+	ld a, [hli]
+	ld e, a
+	ld d, [hl]
+	ld hl, VTiles2 tile $50
+	lb bc, BANK(PackFGFX), 15
+	call Request2bpp
+	ret
+
+PackFGFXPointers: ; 48e93
+	dw PackFGFX + (15 tiles) * 1
+	dw PackFGFX + (15 tiles) * 3
+	dw PackFGFX + (15 tiles) * 0
+	dw PackFGFX + (15 tiles) * 2
+
+PackFGFX: ; 48e9b
+INCBIN "gfx/pack/pack_f.2bpp"