"origin bug" update

[thumper]

Ian came up with a brilliant patch to the regex technique he's been
using to fix the "origin bug". We hacked on it some more and think
that this is something we can release with.

It doesn't work on image/figure captions, nor embedded HTML.

I've also disabled the "entity patchup" code (which was fixing an
error in our XML parser). Broken "<", ">", "&" chars in the text mean
that we need to re-enable this (and fix the unpacking).

Available in sourceforge/thumper branch.

-Bo