VOL-TESTS

Merge pull request #22 in HDF5VOL/vol-tests from ~JHENDERSON/vol-tests:master to master

* commit '5cf17c29d3dc4b0430d56aff19828fbbb5471d5a':
  Add creation order-related tests for H5Lcopy/H5Lmove
  Fix warning about passing non-const char *
  Add more link copying/moving tests
  Split attribute iteration tests by group, dataset and committed datatype
  Update attribute iteration test to better test creation order
  Update attribute _by_idx function tests