Small wrapper around the WinPTY DLL.
This, for example, should allow a Go app to serve up a Windows "cmd" or "powershell" prompt via WebSocket to xterm.js
Currently requires winpty.dll and winpty-agent.exe to be in the same directory as the compiled Go executable.
These are best obtained from the GitHub releases page, in the msvc2015 package.
The error handling needs a bit of work currently though!