added annotation decorators to all user layer and component classes
fixed up tangle of imports
fixing up unit-tests after introducing annotations
debugging decorator annotations
added resolve_reference decorators to ul object to/from_xml methods
added conversion to SI units from 9ml units
debugged projections.py for new reference resolution
added a test annotation
added annotations to abstraction layer readers and writers
debugged annotation decorator
debugged selection to_xml
Merge pull request #60 from tclose/decorators

Added annotations to (almost) all 9ml elements via decorators
Merge remote-tracking branch 'incf/master'