v0.3.2: a smol bugfix release

I found a few more annoying bugs that were shaken out from the whole PonyORM transition, as well as a couple of bugs in the new shape functionality. There’s probably a few more of these bugs lurking in the codebase (I mean, in addition to the existing bugs I know about), but here’s what’s changed:

• Image shape bugs:
  • Fix some FileNotFound handling on images (so shape errors propagate correctly)
  • Make img_class and class work correctly per the documentation
• PonyORM bugs:
  • Put pessimistic lock around all get-or-creates, (hopefully fixing) a transitory indexing error
  • Fix an error where incomplete category paths weren’t forwarding correctly