Added more options:
--cuda_devices 0,1,2 to set the first three gpus as active.
--cuda_threads 64,64,64 to set the first three gpus to have 64 cuda threads each.
--cuda_blocks 48,48,48 to set the first three gpus to have 48 blocks each.
It is now possible to do cpu mining at the same time as gpu mining (might need to create more versions of the binaries to be able to fully use the cpu hardware extensions, so don't expect perfect performance for now).
-t 0 to disable cpu mining.