Fixed errorhandling/message when no files have been provided.

gba/tools/img2bin.py

@@ -1,12 +1,14 @@
 #!/usr/bin/python
 from PIL import Image
 import sys
+import os
 
 """Convert image to raw binary using Python Imaging Library."""
 
 if len(sys.argv) != 3:
-  print "Usage: %s <source> <target>"
+  print "Usage: %s <source> <target>" % os.path.split(sys.argv[0])[1]
   print "WARNING: It only converts 8x8 pixel images at 8bit the moment."
+  sys.exit()
 
 im = Image.open(sys.argv[1])
 output = open(sys.argv[2], "wb")