Improvements to location information

[jeromesimeon]

Support for parsing location through the compiler is mostly in place. Some additional improvements:

• better location improvements for CTO files (accessed from CTO parser), e.g., for import
• add file information to location when available
• possibly add location information downstream to Q*cert AST -- may be necessary for JavaScript map
• Remove as many (all?) of the use of dummy_provenance

[kach]

• location info for failed enforce, inserted automatically during the ergocalculus compilation step

[jeromesimeon]

Note: having access to file (or "module") information in the provenance is important when dealing with multiple modules so should be considered a feature for contract modularity.