MSMLWarning inherits UserWarning
New Version of Visitor Exporter Framework

* now with dispatching
* bug fix
* api corrected
Mark old exporters as deprecated.

* begin with hiflow exporter
Merge branch 'master' of https://github.com/CognitionGuidedSurgery/msml

* 'master' of https://github.com/CognitionGuidedSurgery/msml:
  Delete color-example.xml.py