Organize the engine/ directory, take 3

Renamed `title` to `movies`.
Moved some functions from `engine/routines/` to their fitting
directories, and cleaned up the base `engine/` directory.
Moved `engine/pokemon/tmhm.asm` back to `engine/items/`.

Made a new subdirectory:
* engine/tilesets: Contains all map-related graphics routines.

engine/routines/predef.asm

@@ -0,0 +1,29 @@
+GetPredefPointer:: ; 854b
+; Return the bank and address of wPredefID in a and wPredefAddress.
+
+; Save hl for later (back in Predef)
+	ld a, h
+	ld [wPredefTemp], a
+	ld a, l
+	ld [wPredefTemp + 1], a
+
+	push de
+	ld a, [wPredefID]
+	ld e, a
+	ld d, 0
+	ld hl, PredefPointers
+	add hl, de
+	add hl, de
+	add hl, de
+	pop de
+
+	ld a, [hli]
+	ld [wPredefAddress + 1], a
+	ld a, [hli]
+	ld [wPredefAddress], a
+	ld a, [hl]
+
+	ret
+; 856b
+
+INCLUDE "data/predef_pointers.asm"