go.wde has a windows backend

[John Asmuth]

Thanks to someone with the github user ID papplampe, go.wde now has a working windows backend! It also uses "github.com/AllenDang/w32", so a thanks goes to Allen Dang, who has posted recently in this forum.

In the near future I'll move the cocoa backend (currently at github.com/skelterjohn/gmd) into the go.wde package too. Then, aside from robustness issues, the main thing to do (with go.wde) is to make keyboard events look the same for all platforms. Right now regular letter typing works, but special keys (delete, control, arrows) have different codes reported on different platforms.