Pdm fields can contain a forward declared Pdm object without the include
file
VizFwk: Added VertexColoring shader to be able to use per vertex color
used from drawableGeo::setColorArray()
Fields with option values implicitly have an index based
seUiValue/uiValue interface. This is commented better. Fields of AppEnum
specialization was not quite in line with the rest of the optionValue
system. That is commented and some ifdeffed code has been added to
highlight what could be done when we dare.
