Document why newTransaction is only called by begin.

We have no C extensions, and therefore do not need to exclude their
derived files in 'MANIFEST.in'.

extended-info -> extension

I'll make the transaction release and then I'll push an update to the ZODB PR that works with the change.

renamed to ``extension``.

Hate bytes

See: https://groups.google.com/forum/#!topic/zodb/U0H1kTh_dY4

URGENT: _extension needs to be settable

  attribute to be settable and it wasn't.

Run docs doctests in travis

I need this for some work I'm about to do so...

Yay, doctests work in travis

Also cache eggs

Because sphinx doesn't work with it.

Also, I wonder if scripts can be multiple lines.

Transaction meta data cleanup

Convert to unicode if bytes are given.

  defined to be text (unicode) as apposed to Python the ``str`` type.

- Added the ``extended_info`` transaction attribute which contains
  transaction meta data.  (The ``_extension`` attribute is retained as
  an alias for backward compatibility.)

  The transaction interface, ``ITransaction``, now requires
  ``extended_info`` keys to be text (unicode) and values to be
  JSON-serializable.