ported all urdf documentation from drake.pdf to DrakeURDF.xsd , but also made some changes which became obvious when writing the schema tool.  Still need to modify the parser to comply. Also need the documentation for the parameters and for Andres' collision groups tags.
ported all urdf documentation from drake.pdf to DrakeURDF.xsd , but also made some changes which became obvious when writing the schema tool.  Still need to modify the parser to comply.
Also need the documentation for the parameters and for Andres' collision groups tags.

git-svn-id: cf55bc44fb097054a32fc70455a459c940dbbffc@7255 c9849af7-e679-4ec6-a44e-fc146a885bd3

crogers3/drake,astrorog/drake,thientu/drake,sheim/drake,crogers3/drake,billhoffman/drake,billhoffman/drake,crogers3/drake,scottviteri/drake,tkoolen/drake,hanssusilo/drake,manuelli/drake,sheim/drake,tkoolen/drake,crogers3/drake,edowson/drake,edowson/drake,psiorx/drake,edowson/drake,tkoolen/drake,thientu/drake,sheim/drake,manuelli/drake,thientu/drake,scottviteri/drake,tkoolen/drake,psiorx/drake,psiorx/drake,manuelli/drake,sheim/drake,thientu/drake,billhoffman/drake,manuelli/drake,sheim/drake,hanssusilo/drake,billhoffman/drake,astrorog/drake,edowson/drake,scottviteri/drake,edowson/drake,sheim/drake,edowson/drake,manuelli/drake,crogers3/drake,billhoffman/drake,psiorx/drake,scottviteri/drake,tkoolen/drake,psiorx/drake,hanssusilo/drake,crogers3/drake,scottviteri/drake,psiorx/drake,manuelli/drake,thientu/drake,astrorog/drake,psiorx/drake,tkoolen/drake,scottviteri/drake,manuelli/drake,edowson/drake,psiorx/drake,thientu/drake,hanssusilo/drake,sheim/drake,astrorog/drake,astrorog/drake,tkoolen/drake,billhoffman/drake,sheim/drake,hanssusilo/drake,thientu/drake,billhoffman/drake,astrorog/drake,crogers3/drake,crogers3/drake,hanssusilo/drake,astrorog/drake,hanssusilo/drake,scottviteri/drake,billhoffman/drake,hanssusilo/drake,edowson/drake