Event Handler Signatures Changed to 'fn(event)'

All event handler signatures changed to 'fn(event)'
eventSource property added to the event object passed
Redundant event source properties removed ('button' and 'viewer'
Documentation updated in MouseTracker
changelog.txt updated
referencestrip.js event handler cleanup
referencestrip.js spacing fix
Merge pull request #254 from msalsbery/Event-Handler-Signatures

Event Handler Signatures Changed to 'fn(event)' (#251)