TransformTool : Fix selection update bug
TransformTool : Fix selection update bug

We were trying to avoid calling `updateSelection()` during drags, but only considering the call made in `preRender()`. Several other call sites can trigger `updateSelection()`, so to cover those too we skip the updates within `updateSelection()` itself.

johnhaddon/gaffer,johnhaddon/gaffer,johnhaddon/gaffer,GafferHQ/gaffer,andrewkaufman/gaffer,hradec/gaffer,andrewkaufman/gaffer,ImageEngine/gaffer,boberfly/gaffer,ImageEngine/gaffer,ImageEngine/gaffer,GafferHQ/gaffer,andrewkaufman/gaffer,boberfly/gaffer,johnhaddon/gaffer,andrewkaufman/gaffer,lucienfostier/gaffer,boberfly/gaffer,lucienfostier/gaffer,boberfly/gaffer,GafferHQ/gaffer,hradec/gaffer,GafferHQ/gaffer,hradec/gaffer,lucienfostier/gaffer,hradec/gaffer,andrewkaufman/gaffer,hradec/gaffer,johnhaddon/gaffer,GafferHQ/gaffer,lucienfostier/gaffer,ImageEngine/gaffer