The Environment layer does not keep its own mapping of custom object types.
If we think it likely that users will want to maintain separate lists of
custom object types between two or more Environments, we can add this
later.
- Test markings functions with both dictionaries and our _STIXBase-derived
classes as input.
- Slightly improve test coverage.
- Drop Python 2.6 support.
This required refactoring parts of the library. Code in __init__.py
merged into bundle.py, which was renamed core.py. Code in other.py was
merged into common.py.
Fixes#40.
Chris Lenk