Added the MultiSelectionMenu widget as a replacement for the SelectionMenu widget. The MultiSelectionMenu adds multiple selection, pythonic accessors and operators, cascadeable menus. A decrecation warning has been added to SelectionMenu.
Updated the .gitignore to include VIM temporary .swp files.
Changed the EnumPlugValueWidget and the FormatPlugValueWidget to use the MultiSelectionMenu.
Added the extension .tmp to .gitignore.
Hid the "enabled" plug from all ImageNodes to bring the interface inline with the scene nodes. In the future it may be moved to a separate tab?
 - Updated the MultiSelectionMenu to use "getSelection" and "setSelection" rather than "getSelected" and "setSelected"
 - Fixed a minor bug.
 - Added the appendToSelection() method.
 - Updated the test benches.
 - Updated the EnumPlugValueWidget and the FormatPlugValueWidget
Fixed a small bug that forced one selection even when a allowMultipleSelection == True
Merge pull request #71 from davidsminor/master

small SceneReader/writer updates, + a branch in SceneProcedural that renders VisibleRenderables
Fixed graphical glitches caused by icons overlapping the edge of the editors on the Gnome desktop. Removed style-setting code from SelectionMenu because it will now inherit the same style from the application.
Updating Changes file.
Added the ChannelMaskPlug.
Added the ChannelMaskPlugValueWidget.
Added test benches for both the plug and widget.

This plug and widget provide a way of choosing a subset of channels from the channels available from an input's channels. The plug provides a method for intersecting it's current selection of channels against a vector of other channels.
merging Johns renderManCoshaders branch
Added the static channelIndex method to the ChannelMaskPlug along with test cases and bindings.
Bumping minor version.
Removing unecessary houdini installs.
Removed an unwanted print statement in the ImageReaderTest case.
Merge branch 'ImageReaderTestCleanup' into ChannelMaskForNodes
Fixed a bug where a selection wasn't being kept when alwaysHaveASelection==True
Changed the ChannelMaskPlugValueWidget to allow no channels to be selected.
Picking up the downstream changes that allow a ChannelMaskPlugValueWidget to have no channels as a selection (for testing purposes)

Merge branch 'ChannelMaskPlug' into ChannelMaskForNodes