Add the validator from the Distributed Array Protocol.
Merge pull request #269 from enthought/feature/add-protocol-validator

Add the validator from the Distributed Array Protocol.
Merge pull request #270 from enthought/bugfix/fix-grid-shape-from-dim-data

Better support for block padded and block cyclic distributions
Merge branch 'master' into feature/even-more-examples-mkness
More general handling of various engine counts.
More explicit code block marking.
Labeling processes by coordinates, not ranks.
Plots labeled by process coordinate.