Include overworld sprites

Created /extras/overworldripper.py and used it to extract overworld sprites and convert them to png files.

extras/overworldripper.py

@@ -0,0 +1,13 @@
+import gfx
+
+def rip_sprites_from_bank(bank, offset=0):
+    file_handler = open("../gfx/overworld/bank" + str(hex(bank))[2:] + ".asm", "w")
+    for sprite in range(0 + offset, 256 + offset):
+        filename = "../gfx/overworld/" + str(sprite).zfill(3) + ".2bpp"
+        gfx.get_uncompressed_gfx((bank * 0x4000 + ((sprite - offset) * 4 * 0x10)), 4, filename)
+        gfx.to_png(filename)
+        file_handler.write("INCBIN \"" + filename[3:] + "\"\n")
+    file_handler.close()
+
+rip_sprites_from_bank(0x30)
+rip_sprites_from_bank(0x31, offset=256)