Working on models API.
Finished implementation of the Models API, need some documentation.
Fixed potential locking issue found by FindBugs
Finished Models API.
Removed charts package.
Updated drawing and AudioModel to use new Model API.
Refactored models a little.
Adapted swing client to new conditions.
Fixed bug in playback logic. Updated the doc accordingly.
Fixed android demo to use new models.
Renamed *.observables -> *.model
Moved model tests to *.model package as well.
Added ResourceNotFoundException to configuration exceptions.
Changed structure of GriegCore project
Fixed misplaced model package.
Added XML parser and some tests
Working on XML validation
XML parser most probably behaves as I wanted now.
Finished "the hard part" of the XML parser.
Added few missing tests for XML.
Documented the XML utilities
Fixed Swing client broken by the schema changes. 
JAXB schema has been moved to separate directory under
src/main/resources.