force persistent and interface eggs in test and interpreter scripts

version # when we're ready to release.

Untested. I'll let travis take the first crack. Man, I need to
figure out tox.

Also, I'm not happy with the config variable names I originally
picked.  I'll fix those after the tests pass.

to make them work on mac.

slots and instance dicts correctly.)

  control maximum sizes for bucket and tree nodes.

Make the Python trees and sets accept an explicit None argument to indicate an open range in keys(), values() and min/maxKey(), as per the interface documentation and the C implementation. Except actually, the C implementation didn't accept a None for mim/maxKey, so make it actually do that.

Items must be in reversed-sorted order.

Fixes #2 (maybe).

Previously, the extra required the 'ZODB3' metapackage:  depending on the
version used, the metapackage could pull in stale versions of **this**
package and 'persistent'.

I don't think we intentionally checked for Python 4.

Broeken version could contain garbage characters.