The diff display is rather slow now, probably because everything is
put into one big pre tag. Before we can fix this, we have to parse the
diff better. For now, just display a message.
This includes the prototype library in the bundle for convenience.
Whenever a new commit is selected, a new Commit object is created that
is going to parse the raw message. From the object we can select
author information, diffs, etc.
Currently there is still a bug with commits without content changes.