0.58.0

• Fixed creation of nodes within Boxes - previously they were added below the root of the script rather than inside the box.
• Fixed unstable scene hierarchy expansion (issue #120).
• Fixed highlighting bugs whereby widgets inside a highlighted tab would incorrectly display an inherited highlight state. This could be seen when dragging a node into the node editor with either nested tabs or a nested VectorDataWidget.
• Fixed PathPlugValueWidget bug where it would attempt to change the value of a read only plug.
• Fixed PathWidget bug where it would still do autocompletion and popup menus even when non-editable.
• Added TabbedContainer.insert() method.
• Generalised the Metadata system to store arbitrary values rather than just descriptions.
• Fixed CompoundPlugValueWidget bug whereby it would error if a summary was provided on a non-collapsible UI.
• Added right-click context menus to enum and checkbox plug uis.
• Added Box plug-promotion feature (#142).
• Removed Gaffer.GroupNode (#164).
• Fixed ordering of parameters in RenderManShader UI (#136).
• Fixed banding and dark edges evident in 2D viewer (#74).
• Fixed awkward zooming of Viewers and NodeGraph (#46).