improved performance on Ethash for Nvidia and AMD GPUs
improved performance on KAWPOW for Nvidia GPUs
decreased stale shares rate on Nvidia GPUs for Ethash and KAWPOW algorithms
removed #3 kernel and added 2 energy efficiency kernels (#5 and #6) on Ethash for Nvidia GPUs
improved kernel auto-tuning, auto-tuning takes into account energy efficiency of kernels
optimized NVML polls to decrease memory leaks caused by recent Nvidia drivers (use --pec 0 to exclude memory leaks completely)