new PMFType and PMF for

discrete uni/multi-variate or categorical uni/multi-variate PMFs as
defined in UncertML
fixed minOccurs values
new CountVariableType and CountDataType
removed redundant ct:Symbol
new IntensityParameterType

and added CountData to discrete data models
distinguish between CategoricalPMFType and

CountPMFType plus fixed some minOccurs