Failing batches stop the dispatch job.
Added LocalDispatcher.Job and LocalDispatcher.JobPool to track running batches.

A handy side effect of the JobPool is that we can fix our test cases which rely on waiting for the background jobs to complete.
Added LocalDispatcher.Job.kill() to terminate a running job.
Added a window for tracking currently running LocalDispatcher jobs.

Fixes #872.
Added CPU and Memory columns to the Local Jobs window.
Added a MessageHandler per job and displaying the messages in the window.

Also added a tab for Details, which currently just shows the dispatcher job directory.
Using weakref in DispatcherWindow.acquire and LocalJobsWindow.acquire

Fixes #1064.
Fixed typo in BranchCreator documentation.
Removed unnecessary InternedString construction from BranchCreator.

This gives a small (2-3%) performance improvement traversing a large scene parented into another large scene.
Added sets support to Parent node.

Most of the work is in the BranchCreator base class, so this puts us in a position to implement sets support for the Duplicate and Instancer nodes as well - when we do, should we use * to match instance numbers rather than make huge sets?

Fixes #1065.

Binary incompatibilities :

	- Added additional virtual methods to BranchCreator
Added outputCameras() function to RendererAlgo.h.

This allows all cameras, not just the primary camera, to be output to the renderer. Also added an overload for outputCamera() which outputs the camera from a specific location.
Made ExecutableRender output all cameras.

This allows secondary cameras to be used for stereo rendering, projections, dicing cameras etc.
Made InteractiveRender support multiple cameras.

Backwards incompatibility :

	- InteractiveRender "updateCamera" plug renamed to "updateCameras". I've done a search and can't find any reference to "updateCamera" in any IE code though.
Added support for per-camera resolution overrides.

These are specified with a "resolutionOverride" V2iData in the camera parameters. There's no way of generating such an override in Gaffer itself right now - this is just to support an internal Image Engine workflow for the moment.
Merge pull request #1067 from johnhaddon/parentSets

Sets support for the Parent node
Merge pull request #1060 from johnhaddon/multipleCameras

Multiple camera support
More OSX friendly stats gathering (hopefully).
Merge pull request #1066 from andrewkaufman/localDispatchUI

Local Jobs UI