* Implement Constant Color blends and init blend states
* Address gdkchan's comments
Also adds Set methods to GpuState
* Fix descriptions of QueryModified
* Implement RasterizeEnable
* Match viewport count to hardware
* Simplify ScissorTest tracking around Blits
* Disable RasterizerDiscard around Blits and track its state
* Read RasterizeEnable reg as bool and add doc