Hybrid Pressure load and save support for PP

This PR adds support for loading and saving PP files with a hybrid pressure coordinate as indicated by an lbvc value of 9. This is a big PR resulting from three people working in collaboration and I'll be happy to split it up if necessary.

Remaining tasks:

- [ ] ~~Determine appropriate value of ```PP_HYBRID_COORDINATE_REFERENCE_PRESSURE```. I've currently set this to unity.~~
- [x] Fix copyright dates
- [x] Reach consensus on direct editing of rules files
- [ ] ~~Fix p/p* scaling on save~~
- [x] Confirm reversal of sigma and delta from blev and bhlev values relative to hybrid height (looks very suspicious to me).