gosam-contrib-higherrank: preliminary rank-6 pentagon support for Golem95C etc.

The commit includes further improvements and bug fixes to higher
ranks including a more generic cache system and a (very) preliminary
support for rank-7 hexagons.

git-svn-id: svn+ssh://svn.hepforge.org/hepforge/svn/gosam/gosam-contrib-higherrank@385 a6e02f90-e1d0-4296-904b-e314d7e4afaa