cpp: tiff: Remove redundant partial template specialisation declarations

Also remove default get/set implementation template and add
UInt16Tag1 specialisation.
cpp: tiff: Declare TIFFField if not available
cpp: tiff: Drop explicit TIFFField declaration
Revert "cpp: tiff: Drop explicit TIFFField declaration"

This reverts commit 6d2750e56420cfd14886b712da698a1b0e2aef14.
Merge branch 'develop' of https://github.com/bjoernthiel/bioformats into develop