common source for sparc mappings

[tgbugs]

We have foundry-interlex mappings, the internal mappings in the python code, and the mappings from the protcur working sheets. These all need to land in a single place so that we can have version control of these.

The two current sources of mappings in the code itself.

1. https://github.com/SciCrunch/sparc-curation/blob/master/sparcur/mapping.py
2. https://github.com/SciCrunch/sparc-curation/blob/master/sparcur/normalization.py there are some mappings in here despite that there probably should not be.

In principle mappings.py has been written so that we can source the mappings from external sources. One issue is that these mappings currently do not account for context, you have to know where it is appropriate to use a particular mapping function.

@jgrethe I'm considering exporting the mappings from InterLex/foundry as a ttl file so that we can version it and integrate it with everything else.