GafferDeadline 0.59.0.0

• Breaking Change : Changed plug type of extraDeadlineSettings and extraEnvironmentVariables to AtomicCompoundDataPlug. This allows the values to be set by registering userDefault metadata and prevents adding non-sensical data such as shaders to these plugs. It will break existing expressions connected to these plugs. The broken expression nodes will still exist and can be reconnected by replacing the __disconnected = IECore.CompoundObjectData( YourCompoundData ) variable assignment with parent[YourNodeName]["dispatcher"]["deadline"]["extraDeadlineSettings"] = IECore.CompoundData( YourCompoundData ) or parent[YourNodeName]["dispatcher"]["deadline"]["extraEnvironmentVariables"] = IECore.CompoundData( YourCompoundData )