Nim 1.6.4 release candidate

[moigagoo]

Can't install 1.6.4 on Windows:
    
    
    choosenim "#version-1-6-4"
    Downloading Nim version-1-6-4 from GitHub
    [##################################################] 100.0% 0kb/s
     Extracting version-1-6-4.tar.gz
       Building Nim #version-1-6-4
       Warning: Building from latest C sources. They may not be compatible with 
the Nim version you have chosen to install.
    Downloading Nim C sources from GitHub
       Cleaning failed build
    winhttp.nim(57)          checkHRESULT
    Error: unhandled exception: HRESULT: 80072F78 [PuppyError]
    
    
    Run