This is the core of the Rainpress Compressor (minifier, really) by Uwe L. Korn,
loosely repackaged as a plugin.  The original code may be found here:
    http://code.google.com/p/rainpress/

Currently, this is based on the v1.0 release (SVN version 54 - March 20, 2008)

I've stripped out all the command-line stuff and just kept the core compressor.
This has the added benefit of not requiring anything (the full version requires
GetText).