Add translation of GridCollections to Multiblock into reader.

Still have to make spatial collections stripe in parallel.
Writer does not yet now what to do when it is given a multiblock.

Change-Id: Ibe272b46cd9264884e88ef7fb278b0cc2e05a95c
multiblock and temporal are now working

The large ARL dataset can now be read and written, but translation
errors in the atomic data sets make it nonsensical. Those will
be fixed in testing.

Still have to enable parallel sieving.

Change-Id: Icadc284a91a97f1d4ec0cdd6ffa2e6a92ad5424e