Add a test for checking that the required directory count is valid

We can't reliably test for the required directory count being too large,
but the test will fail if the directory count is too small.
MDBService: fix file initialization for mapped files
InCell: put the current file first on the used file list

This is important for datasets with .im files, which are not usable by setId.
L2D: remove unnecessary override of getRequiredDirectories

All files are in the same parent directory, so there is no need to
preserve additional directories.
Visitech: use Location instead of File
Fix Zeiss TIFF reader and CaseInsensitiveLocation to work with mapped files
Prairie: use Location and RandomAccessInputStream instead of File
FV1000: fix handling of mapped files
Tidy up the required directory test
Fix use of File.separator in a regex
FV1000: fix .pty stream detection for .oib files
Final set of fixes for testing getRequiredDirectories
Make sure that the file to initialize is non-null
Merge pull request #1154 from melissalinkert/leica-filter

Leica: prevent exception when linking EmissionFilter
merge develop -Dorg -Ijburel/openmicroscopy:qa-submit-new -Ssuccess-only: PR 1296 (Add test for getRequiredDirectories)
merge develop -Dorg -Ijburel/openmicroscopy:qa-submit-new -Ssuccess-only

Repository: openmicroscopy/bioformats
Excluded PRs:
  # PR 1309 melissalinkert 'Allow tile-based access of large JPEG-2000 images' (exclude comment)
  # PR 1249 PremyslFiala 'ND2 - Bug fixes' (user: PremyslFiala)
  # PR 857 melissalinkert 'Initial support for Zeiss .lms files' (label: exclude)
  # PR 1161 sommerc 'Initial CellH5 Reader class' (user: sommerc)
  # PR 858 melissalinkert 'Initial support for Veeco AFM data' (label: exclude)
  # PR 1362 melissalinkert 'Make FormatReader's RandomAccessInputStream transient' (label: breaking)
  # PR 816 melissalinkert 'Add support for multi-channel Volocity Clipping datasets' (label: exclude)
  # PR 1177 rleigh-dundee 'specification: Add metadata for HDF5 embedding' (exclude comment)
  # PR 1015 qidane 'Messy binary' (exclude comment)
  # PR 1265 qidane 'New units' (label: breaking)
Updating 613124f..04a09b0
Previously merged:
  # PR 1154 melissalinkert 'Leica: prevent exception when linking EmissionFilter'

Merged PRs:
  # PR 1296 melissalinkert 'Add test for getRequiredDirectories'

Generated by OME-5.1-merge-push#495 (http://ci.openmicroscopy.org/job/OME-5.1-merge-push/495/)