ShaderSwitchUI : Fix NodeGraph representation.
ShaderSwitchUI : Fix NodeGraph representation.

It was presenting the whole input array as a single plug rather than presenting the children. This gave the appearance of connections being missing and new connections being impossible, although at the API/file level all was working as intended.

Fixes #1461.

lucienfostier/gaffer,ivanimanishi/gaffer,lucienfostier/gaffer,chippey/gaffer,johnhaddon/gaffer,hradec/gaffer,hradec/gaffer,andrewkaufman/gaffer,GafferHQ/gaffer,appleseedhq/gaffer,chippey/gaffer,lucienfostier/gaffer,appleseedhq/gaffer,GafferHQ/gaffer,andrewkaufman/gaffer,boberfly/gaffer,johnhaddon/gaffer,GafferHQ/gaffer,GafferHQ/gaffer,ImageEngine/gaffer,chippey/gaffer,johnhaddon/gaffer,GafferHQ/gaffer,ivanimanishi/gaffer,boberfly/gaffer,ivanimanishi/gaffer,boberfly/gaffer,ImageEngine/gaffer,andrewkaufman/gaffer,lucienfostier/gaffer,appleseedhq/gaffer,johnhaddon/gaffer,ImageEngine/gaffer,ivanimanishi/gaffer,hradec/gaffer,andrewkaufman/gaffer,johnhaddon/gaffer,boberfly/gaffer,ImageEngine/gaffer,appleseedhq/gaffer,hradec/gaffer,hradec/gaffer,andrewkaufman/gaffer,chippey/gaffer