v1.7.7

What's Changed

• Updated to IGRF-14 model by @nickssl in #1108
• Set min time of IGRF model to 1965 (previously, it was 1970) by @nickssl in #1113
• Added minvar_matrix_make outputs for eigenvalues and basis vectors
• xyz_to_polar now works on tplot variables
• Updated required version of pytplot-mpl-temp to support wildcards in many utilities (options, ylim, zlim, time_clip, deflag, degap...)
• Updated several test suites to exercise updates to minvar_matrix_make, xyz_to_polar, tplot variable wildcards
• Updated documentation on pyspedas.readthedocs.io

Full Changelog: v1.7.6...v1.7.7