Implemented a full "generic" pygmt spider plot, with dynamic topography, coastlines, moment tensor and header option. The backend comes with a utility class where most individual functions are stored.

Added a new plotting function for normalized cross-correlation, working with the default and pygmt backend.

Fixed text placement. Will now be automatically placed based of figure dimensions / latitude extent, and longitude.

Updated cross_correlation docstring.

Introduced histogram gaussian normalization for background topo map to avoid too-harsh contrasts. Change moment tensor coloring.

Added complete docstring for the pygmt functions.

Changed the function so that it can handle all combination of text + latex math expressions.

Added a few key functions for the attributes pygmt plotting backend. Compilation was tested with the building script and html renders as expected.