Add routine to add modules by name.
Try to avoid loading modules that are already loaded.
Rename dynamically created module from Parameters to Params.
Move functions for Parameters to module Parameters; add findAtomic.
Add operations to add modules one-at-a-time.
Make a module_loader class that caches parsed and desugared modules.
Add loaded modules one at a time.
Simplify code.
Avoid duplicating code when processing submodel import notes.
Add new builtin get_modifiable_index.

Also move parameter builtins to Parameters.hs.
Fix unused type signature.
Add new builtin get_modifiable_for_index.
Add Range IntegerInterval.
Add some new find* functions.