cpp: tiff: Correct a number of compiler warnings

- explicitly initialise all pointers
- explictily cast where numeric types differ
- use 64-bit offset type when using bigtiff
cpp: tiff: Use 64-bit offsets externally, 64/32 internally

Internal implementation depends upon BigTIFF support by libtiff; the
external interfaces are always 64-bit.
cpp: tiff: Tests initialise all variables and use correct types
merge develop -D org: PR 857 (Initial support for Zeiss .lms files)
merge develop -D org: PR 858 (Initial support for Veeco AFM data)
merge develop -D org: PR 981 (Ignore namespaces when filling in an XMLAnnotation's Value)
merge develop -D org: PR 983 (Woolz: make sure the service is initialized when calling openBytes (rebased onto develop))
merge develop -D org: PR 1108 (MRC: fix handling of mode 16 data (rebased onto develop))
merge develop -D org: PR 1116 (cpp: Add TIFF support (1))
merge develop -D org: PR 1138 (Lots of Zeiss CZI fixes (rebased onto develop))
merge develop -D org: PR 1154 (Leica: prevent exception when linking EmissionFilter)
merge develop -D org: PR 1155 (Memoizer errs (rebased onto develop))
merge develop -D org

Repository: openmicroscopy/bioformats
Excluded PRs:
  # PR 1136 melissalinkert 'Add initial support for reading BinaryOnly OME-TIFF datasets (rebased onto develop)' (label: exclude)
  # PR 1123 melissalinkert 'Add a reader that accepts a file containing a file pattern' (label: exclude)
  # PR 1054 qidane 'Additional annotation points throughout the model' (exclude comment)
  # PR 1141 LeeKamentsky 'Reader for Amaris FlowSight .cif format' (label: exclude)
  # PR 1015 qidane 'Messy binary' (exclude comment)
  # PR 816 melissalinkert 'Add support for multi-channel Volocity Clipping datasets' (label: exclude)
  # PR 978 berl 'Add writing of .v3draw format for easy loading with Vaa3D.' (user: berl)
Already up-to-date.

Merged PRs:
  # PR 857 melissalinkert 'Initial support for Zeiss .lms files'
  # PR 858 melissalinkert 'Initial support for Veeco AFM data'
  # PR 981 melissalinkert 'Ignore namespaces when filling in an XMLAnnotation's Value'
  # PR 983 melissalinkert 'Woolz: make sure the service is initialized when calling openBytes (rebased onto develop)'
  # PR 1108 melissalinkert 'MRC: fix handling of mode 16 data (rebased onto develop)'
  # PR 1116 rleigh-dundee 'cpp: Add TIFF support (1)'
  # PR 1138 melissalinkert 'Lots of Zeiss CZI fixes (rebased onto develop)'
  # PR 1154 melissalinkert 'Leica: prevent exception when linking EmissionFilter'
  # PR 1155 joshmoore 'Memoizer errs (rebased onto develop)'

Generated by OMERO-5.1-merge-push#278 (http://ci.openmicroscopy.org/job/OMERO-5.1-merge-push/278/)