Enhance exception messages and check OIB format version.
Add filename extension to parse_path dictionary.
Generalize validate_oibpath() to validate_filepath().
Introduce generic ImageDataOlympus() class.

This is meant to provide the common basics for the OIF and OIB subclasses.
Make ImageDataOIB inherit from ImageDataOlympus to reduce redundancies.
Update description of ImageDataOIB.setup_parser().
Change ImageDataOIF to inherit from the new ImageDataOlympus superclass.
Fix log messages and leftover call.
FIXME