Merge 'master' from xdag.me/xdag.git

Updates from version T13.856 to T13.865.

Rename Win64 files and paths from 'cheatcoin' to 'xdag'

- Renamed `cheatcoin` file and paths to `xdag`
- Updated project to build with new file paths
- Removed hardcoded paths to OpenSSL, pthread; replaced with environment variables

Update README.md