FF: aperture.contains() now working

plus:
- simplify the shape logic
- log error if unknown shape
- default size=1
- some testing of shape options
BF: fix pos in convertToPix call from .contains()

Good if someone else could double check that this is the right fix.
DOC: comments in aperture
Merge pull request #548 from jeremygray/master

ENH: aperture.contains() now available