Fixed LocalDispatcher to quote command line arguments.
Fixed LocalDispatcher to ignore "ui:" prefixed context variables.
Merge pull request #1069 from johnhaddon/dispatchFix

LocalDispatcher fixes
added python error catching to ConnectionBinding, to prevent crashes
Merge pull request #1074 from davidsminor/signalPythonExceptions

added python error catching to ConnectionBinding, to prevent uncaught exception crashes
WIP
Selection management in SceneGadget.

No interactive selection though - I think we'll do this outside of the SceneGadget.
Method definitions for SceneGadget.
SceneGadget responding to Context changes.
WIP
SceneView expansion working again.
SceneView collapsing working again.
SceneView selection tool code. Not yet coupled to SceneGadget.
SceneGadget objectAt() WIP.
Updated GafferUI for recent IECoreGL::HitRecord API change.

The HitRecord now simply stores an integer ID rather than an InternedString name, so we use NameStateComponent to provide a mapping to names. In future, we may ditch the use of names entirely to avoid the unnecessary construction of many InternedStrings.
Implemented SceneGadget objectAt() and objectsAt().
SceneView selection tool now operational.