A model is needed for context (i.e., for access to variables, constants, labels, etc.).
Previous methods required the user to pass in a ModelInfo object for this purpose.
These new methods should now be preferred to the old ones.
Calls have been replaced where possible, including a slight reorder of parsing/loading in PrismCL.
In the GUI, the parsed model is cached locally in various places but should always
be the same as the one currently loaded into PRISM.
This is part of an ongoing effort to reduce the extent to which code is
tied to the PRISM language (i.e., ModulesFile) specifically.,
and to push make the Prism object more generally useful as an API.
Dave Parker
f97cd22744