Fix a bug and release a new version based on Claymore 15.0

  1. Fix a MessageBox suspend bug whic will cause the nodevfee.dll to stop working sometimes.
  2. (1)Claymore 15.0 main changes: now miner supports up to #384 epoch (4GB DAG size). Note that previous versions support up to #299 epoch, you will not be able to use old versions after #299 epoch. (2)added support for Navi cards (ETH-only mode).

Remove bundled miner software, just keep core files

Change some typo

Modify README

修改了README样式