[vtk-developers] A new internal Start method for interactors

[David Gobbi]

The interactors are core classes, so I'm bringing this to the list:

The Start() method for every single interactor class had a check for the
"HandleEventLoop" ivar, so I've moved the check into the interactor
base class, and added a new StartEventLoop() method that Start()
calls for the specialized classes to run the OS-specific event loop.

Gerrit patch is here:
http://review.source.kitware.com/#/c/17567/

Comments welcome.

 - David