feat(Synchronizer): Change Scope of Event handlers (#1291)
feat(Synchronizer): Change Scope of Event handlers (#1291)

Set fireEvent and onEvent functions from anonymous inner functions to object keys, to allow
consumers to monkeypatch the functions of need be.
chafey/cornerstoneTools,cornerstonejs/cornerstoneTools,cornerstonejs/cornerstoneTools,cornerstonejs/cornerstoneTools