Various related changes, including refactoring part of dataset creation, and reworking how layout versions are calculated.
Needs more testing of filters that create very large chunks, but that will need code to turn it off in cases where we can't allocate >4GiB buffers. I tested this manually by increasing the expansion ration in the expand2 test in dsets, and it passed everything up until it tried to expand the datasets with H5Dset_extent() and my laptop ran out of disk space.
We should add code and testing to handle the case where the "size of size" is set less than 8 bytes. This is not a new issue, since it can be set to 2.
I will file issues for these, but I don't think they are necessary for the release.
Neil Fortner
1093a18c18