SilentMiner-VolVeR

• Changed process creation from undocumented API calls to direct system calls
• Improved GPU limit sleep time accuracy for powerful GPU cards
• Removed ETH from the preset list due to the ETH merge from PoW to PoS
• Added EthereumPoW (ETHW) fork of ETH to the preset list
• Fixed many miscellaneous bugs
• Updated xmrig