Depthbias node to avoid to Fix Z-Fighting Issues

@gregsn - is is feasible to easily implement the dx9

D3DPRASTERCAPS_DEPTHBIAS
D3DPRASTERCAPS_SLOPESCALEDEPTHBIAS

renderstates? they somehow escaped exposure by vvvv…

http://msdn2.microsoft.com/en-us/library/bb205599.aspx

the following article explains the issues quite well. but i see the discussed alternatives somehow more difficult to use than zbias hack…
http://www.intel.com/cd/ids/developer/asmo-na/eng/168495.htm?prn=Y