Fix virtual destructor compiler warning

A 'delete' was called on a virtual object, Interpolator *p. Presumably,
p will actually point to a derived interpolator, say
CartersianInterpolator. In this case calling evoking a 'delete' on p
should call the destructor of the derived interpolator.
Added an introduction to using matplotlib with cartopy. More work
needed.
Major enhancements to the docs.
Major enhancements to the docs.
Merge pull request #79 from pelson/mpl_docs

Added introductory matplotlib docs.
Added some of the basic data to the repo.
Merge pull request #80 from pelson/setup_fix

Added some of the basic data to the repo.
Fixed a compatibility issue, and added a result image.
Major coastline speedup for multi-plots.
Major performance boost for contour.
Fix to remove unwanted line across Orthographic projection.
Added tests for the performance improvements.
Merge pull request #83 from pelson/performance

Major coastline speedup for multi-plots.
Merge pull request #84 from esc24/orthographic_fix

Fix to remove unwanted line across Orthographic projection.
Documentation review actions.
Added land filling option.
Remove obsolete SVN files
Merge pull request #87 from rhattersley/remove_svn

Remove obsolete SVN files
Removal of unused path_interpolation function.
removed unused class and instance