Apply matplotlib rc parameters correctly throughout

[philippjfr]

I've long struggled with the correct way to apply rcparams in matplotlib, I now think a decorator which is applied during axis/figure creation, for all initialize_plot and update_frame calls and during rendering is the best approach.

Fixes #1222

[philippjfr]

Ready for review.

[jlstevens]

Seems like a sensible approach and I am happy with it as long as it works - preferably better than before!

My only comment is that I think mpl_context should be called mpl_rc_context to be explicit.

[jlstevens]

I suppose my only other comment is that it might be nice to test - if it is easy enough to set up such tests.

[jlstevens]

Just rename mpl_context to mpl_rc_context and consider adding some tests if possible. Otherwise looks good.

[philippjfr]

Ready now, pretty sure the coverage report is false, when I click through to it, it doesn't actually tell me which files now have reduced coverage.

[jlstevens]

Ready now, pretty sure the coverage report is false

Yeah, a -1.4% coverage change is surprising.

Anyway, looks good and I'll now merge.