diff: Start work on image display

kittens/diff/images.py

@@ -0,0 +1,20 @@
+#!/usr/bin/env python
+# vim:fileencoding=utf-8
+# License: GPL v3 Copyright: 2018, Kovid Goyal <kovid at kovidgoyal.net>
+
+import shutil
+import warnings
+
+
+class ImageSupportWarning(Warning):
+    pass
+
+
+def images_supported():
+    ans = getattr(images_supported, 'ans', None)
+    if ans is None:
+        ans = shutil.which('convert') is not None
+        images_supported.ans = ans
+        if not ans:
+            warnings.warn('ImageMagick not found images cannot be displayed', ImageSupportWarning)
+    return ans