Aribitrary axis distribution

[mpokorny]

Add support for arbitrary distribution of an axis across the process grid. Distribution could be described as a list of axis values and ranges, e.g, 1, 3-5, 8 would select values 1, 3, 4, 5, and 8. As for implementation, this gets tricky where fileviews are defined and set, since there is no regularity. Perhaps the best option is to create a sequence of fileview datatypes, and some way to iterate through the sequence (this scheme could generalize the current implementation.)