package.bash packages the Go toolchain for Windows in 
zip and installer (msi) format. 

Dependencies
============
- WiX Installer XML (WiX) toolset: http://wix.sourceforge.net/
- 7Zip command-line: http://www.7-zip.org/download.html
- MinGW/Msys tools

Unzip and place 7za.exe in msys' bin directory.
Add the WiX bin directory to PATH.

Packaging
=========
- have a go tree at $GOROOT
- make sure $GOBIN=$GOROOT\bin or is empty
- make sure $GOARCH=386 or $GOARCH=amd64
- select appropriate version "hg up -r ..."
- build go "cd $GOROOT/src; ./all.bash"
- create Windows packages "cd $GOROOT/misc/windows; ./package.bash"