Const' declared instances of Vtr::Array do not protect the pointer held
privately by the class properly. In order to force the compiler to
protect this pointer, we removed all non-const accessors from Vtr::Array
(now renamed Vtr::ConstArray) and moved them to a child class (Vtr::Array),
which requires const_cast<> operators internally to allow access.
The change & renaming is then propagated to all internal dependencies.
- split Far::PatchDescriptor into its own class (mirrors Far::PatchParam)
- hide PatchArray as a private internal structure
- add public accessors patterned after Far::TopologyRefiner (returning Vtr::Arrays)
- propagate new API to all dependent code
note: some direct table accessors have not been removed *yet* - see code for details
