CompoundPlugValueWidget remembers collapse state.

State is stored on a hidden, non-serialisable plug on the node, and updated whenever the collapse status changes. On building a new ui, we restore any previously stored state.
Node Editor remembers current tab.

Node Editor stores the last viewed tab on a non-serialisable plug on the node, and uses it to set the current tab when generating new uis.

Fixes #87.
Slowed wheel zooming in ViewportGadget.

Fixes #200.
Fixed crash when dragging nodes.

This occurred when a "dangling" connection existed without a source nodule, as happens when inputs come from outside a Box or a node has been hidden in the GraphGadget.
Merge pull request #214 from johnhaddon/dragReconnectCrashFix

Fixed crash when dragging nodes.
Improved NodeEditor node labelling.

The node name field is clearly labelled as such, and an additional info icon provides the node type and description.
fixed a bug in the NodeGraph where setTitle() was having no effect
Merge branch 'master' of https://github.com/ImageEngine/gaffer
Added and empty LINKFLAGS option to SConstruct.
Without it, SCons won't respect if LINKFLAGS is specified in a config file.
Merge pull request #216 from johnhaddon/linkFlags

Added an empty LINKFLAGS option to SConstruct.
Merge pull request #196 from johnhaddon/uiCollapseState

Remembering UI state
Merge pull request #215 from johnhaddon/nodeEditorNodeLabel

Improved NodeEditor node labelling.
Updated Changes and bumped minor version.
Fixed a bug with the default format where it wasn't getting passed into the context of the ImagePlug worker threads.
Added the extension *.~ to .gitignore.
Merge pull request #223 from goddardl/DefaultFormatBug

ImagePlug Context Bug.
Merge branch 'master' into noduleLabels.