Ability to hide interactions for certain participants

[nickmcdowall]

A suggestion was given to be able to hide certain participants from being included on a sequence diagram. This may be useful to simplify some diagrams by hiding internal participants that may be included via interceptors, reflection etc. but don't add value to the diagram.

Another benefit it that it may be useful to generate high level diagrams alongside more detailed diagrams - therefore perhaps the hide list should/could be provided per scenario??