Transformed shell script into perl script and improved it to allow

Transformed shell script into perl script and improved it to allow
diffs to depend on other diffs.  Diffs are made locally now (not
using cvs) which makes them faster as well as making the date
header compatible with patch's -Z option (which we now use to
avoid useless changes to the diff headers).  Automatically exclude
generated files from the diff (such as proto.h).