The ``PolyQuadMesh`` class requires full 2D arrays of values
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Previously, if a masked array was input, the list of polygons within the collection
would shrink to the size of valid polygons and users were required to keep track of
which polygons were drawn and call ``set_array()`` with the smaller "compressed"
array size. Passing the "compressed" and flattened array values will no longer
work and the full 2D array of values (including the mask) should be passed
to `.PolyQuadMesh.set_array`.
