Licensing, Changelog and other release engineering for PyPI release
Remove an awkward note from README

This was implemented in 0.2
Fix bad example on intro

There's actually a bug here, which was fixed in 0.3.  Add a test to prove
that it works.
Complete normalize.selector documentation
More work on the 'diff' documentation

Looks like I already went over this once.  Visitor can be next release :-)
Misc. documentation updates

Some internal diff functions (essentially architecture documentation), also
make Record reference docs appear again.
Improve informal stringification for Diff, MultiFieldSelector

The informal representation of these two types was insufficient for
practical use; instead of cutting the details, represent them in a tree
form.  This makes them more useful, and make it less necessary to resort to
the (very verbose) repr() form.
Changelog new changes for 0.4.4 release