Merge BTCW code into BTC 0.26x baseline

[bitcoin-pow]

BTCW repo was synched with latest BTC 0.26x branch. Merge the latest 0.23x BTCW code into the following branch below. Modify the GUI by adding the mining icon; when the user clicks the icon, they can enable/disable mining and view mining statistics such as CPU loading and number of hashes per second. Going forward the GUI will be the exact same as BTC except for the additional mining icon. https://github.com/bitcoin-pow/BitcoinPoW/commits/26.x

[bitcoin-pow]

Pushing updates to the following branch: https://github.com/bitcoin-pow/BitcoinPoW/tree/26.x_btcw

Release Candidate: https://github.com/bitcoin-pow/BitcoinPoW/pull/34

[bitcoin-pow]

Merge completed: https://github.com/bitcoin-pow/BitcoinPoW/tree/v26.1.0_final