v0.4g STABLE NVidia Build

With this release I have removed some cuda code that I think was limiting the amount of block/thread combos.
I also fixed the -cs switch so it can be used with any combo of cpu flags or ocl flags.

FOR MULTI GPU TESTERS:
to select a different block size and thread size for each card try this:
If you had three cards:
-t 0 -cb 64 64 128 -ct 32 32 64 -cs -cd 0 1 2

#Added
Gtx 500 series compatibility with v0.4g_sm20