made shaders accept inputs from boxes
fixed shader parameterHash propagation through boxes
added a comment
just used the source method instead of repeatedly calling getInput()
corrected usage of source method
added unit test for hash propagation through boxes
added comment about box connections
added test to make sure you can connect renderman shaders to dangling plugs on boxes
Merge pull request #501 from davidsminor/graphpherAdaptorNetworksFixes

Graphpher adaptor networks fixes