Fix typo in plotting code and enable GitHub actions

This fixes a typo in the plotting code that would cause an exception.

The repository has also been transitioned to using GitHub actions for CI testing, and additional work has been done to fix ReadTheDocs builds.

Write Grids

Add methods to GraspGrid and GraspField to write out to GRASP .grd files.

Add reflectance calculations

Add reflectance calculations

Add scaling of fields

v0.3.4

Bump version: 0.3.3 → 0.3.4

Bug fixes to plot

v0.3.3

Bump version: 0.3.2 → 0.3.3

Add plotting functions

Add useful functions and functionality for plotting and combining different grids and fields.

Summing of fields and grids

Adds a method for summing fields within a grid object (e.g. to make an incoherent sum over frequencies) and a function for adding grid (e.g. to add one analysis output to another).

Add analysis module

Add in the analysis submodule, with a number of fixes to make it usable.

Tor file parsing

Changes ownership to Smithsonian GitHub Team.
Incorporates a working torfile parser (largely undocumented).

Cuts and Grids

Cuts and Grids working. Push to PyPI