Made a few other changes to make reading more clear
Paracrystal models (all 3)
Fixed code for FCC and BCC
Fixed docs for FCC and BCC
Updated docs for FCC, BCC, and SC with the full equations used from the papers
Removed the warning that the model might be wrong.
The second bullet fixes a long standing problem with the paracrystal models (not just the documentation)
This cherry picks changes to two types of models.