Finished separating the old function into two, one to interpolate data onto new geometries and one to write zone as arbitrary file types.

fixed some errors in shell points. also fixed it so the shell and trajectory geometries get their extra variables.

Formatting and dummy code for geometry functions. For trajectory/tecplot format we should do things a little different.

Tecplot documentation update

See merge request !5

Made tecplottools.apply_equations more robust, anticipated some different formats in equations files

- Google style docstrings use `Args:` and not `Arguments:`
- Stick to markdown *everywhere*.
- The first line in a big docstring `"""` is always a one line summary

Please confirm before I merge :).