Add some bits and pieces for git hooks

This is a legacy commit from before 2015-03-01.
It may be incomplete as well as inconsistent.
See COPYING.legacy and README.history for details.
prepare-commit-msg.trunk.refuse is the only useful hook currently

SVN Path:     http://gpitrsvn.gpi.uni-karlsruhe.de/repos/TFSoftware/trunk
SVN Revision: 5518
SVN UUID:     67feda4a-a26e-11df-9d6e-31afc202ad0c