* Support pcolormesh shadings other than "flat"

shading="gouraud" and the (new in matplotlib-3.3) "nearest" shading
require the array to be sliced differently, and not flattened.

* Tests for shading argument to Pcolormesh

* Fix slicing in shading=="auto" branch

* Handle case where shape of Z is (nx-1)*(ny-1)

This is the case matplotlib is better set up to handle, and uses X and Y
as the positions of the cell corners to be colored according to the
value of Z. This case needs to use standard slicing from
Block._make_slice() instead of the workaround in
Pcolormesh._make_pcolormesh_flat_slice().

* Test shading="flat" with corner positions passed in

* Test shading="auto"

…t-makaro#54)

* Fixed BunchOFiles writer by downstreaming the code that was deleted upstream.

* Update CircleCi

* Fix ragged array checks

* patches for 0.4.3 release

* 0.4.3 patchnotes

* Fix html docs build