Remove empty keys for FileRegistry
Style: use 'tables.' instaed of 't.'
Close all handlers before trying to remove the file
Use integer division for computing indices
Fixed a warning related to non-unicode filenames
Set min_hdf5_version to 1.8.5. See gh-323 and gh-326
Revert "Set min_hdf5_version to 1.8.5. See gh-323 and gh-326"

This reverts commit 62593193717e53015508e45a6dcc4d4a0567458a.
Style
Inplement the strict open policy for files
Document the limited support to HDF5 < 1.8.7
Improved File.open_count docstring
Fix version check
Make the HDF5 version check more general
Merge branch 'open_checks' into develop
Better description of backward incompatible changes in the RELEASE_NOTES