0.11.0

• GafferUI.Image() constructor now accepts unicode strings.
• Gadget, NodeGadget and StandardNodeGadget may now be derived from in Python.
• NodeGadget.registerNodeGadget() may now be called from Python, passing a callable for the creation function.
• New GafferUI.ImageGadget class allows images to be displayed in zoomable gadget uis.
• GafferUI.StandardNodeGadget can now be customised using a new setContents() method. This allows the central region of the node to be replaced with custom gadgets on a per-node basis. See startup/gui/graphs.py for example code for customising with an icon (note that this is waiting for a PNGImageReader to be available in cortex).