Changes in torchANNBasedDG3DMaterialLaw

Added 4 new properties to the child class torchANNBasedDG3DMaterialLaw
that store mean and stdev of Radius and Cell size

Added a second constructor in the same class that uses the default constructor as a delegating constructor, and then initializes the additional
parameters.

Modified the default constructor so it initializes the extra properties
to -1, (consistency for legacy code)

Made corresponding changes in the swig constructor so it exposes both
constructors that can be used based on the number of arguments keeping
the name same (consistency for the legacy code)

Code compiles and previous example works.

Mohib