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/tilesets/mapgroup_roofs.asm

@@ -0,0 +1,20 @@
+LoadMapGroupRoof:: ; 1c000
+	ld a, [wMapGroup]
+	ld e, a
+	ld d, 0
+	ld hl, MapGroupRoofs
+	add hl, de
+	ld a, [hl]
+	cp -1
+	ret z
+	ld hl, Roofs
+	ld bc, 9 tiles
+	call AddNTimes
+	ld de, vTiles2 tile $0a
+	ld bc, 9 tiles
+	call CopyBytes
+	ret
+; 1c021
+
+
+INCLUDE "data/maps/roofs.asm"