Xmas bug fix release

Config files from 2.1.0 are compatible and can be reused.

Changelog:

• NVIDIA backend
  • add cuda 9.1 support #549
  • better error handling #464
  • fix static compile with non GNU compiler #652
• Other
  • fix timer issues #445 #664
  • fix windows compile #449
  • improve UAC dialog #649
  • improve documentation

Necessary prerequisite

If the application does not start properly, please make sure that Visual Studio libraries are installed.
You can download them from https://go.microsoft.com/fwlink/?LinkId=746572

Funds request

... for a exciting project to take Monero mining to a new level - see if you like them:

GUI Miner