The default OpenLayers.js file, minified, weighs in at a whopping 943kb uncompressed.
With gzip compression it's still over 200kb, so we're building a stripped-down copy
with just what we need.

Docs on how the stripping process works:
http://docs.openlayers.org/library/deploying.html

To recreate this OpenLayers.js file:

  # get yui-compressor (install from apt, or set up a shell script or alias to the jar)
  # download and decompress OpenLayers-2.10 zip or tgz
  make clean && make

If necessary, change the relative path to the OpenLayers source directory in the Makefile.