ant: release target works when run in a submodule

Check for presence of .git, not whether it's a directory.
Fix tiled TIFF saving when partial tiles will be used

If the image width and/or height are not multiples of the tile
dimensions, then the last tile in each row or column will be smaller
than the others.  This commit prevents an exception when that is the
case.
Restrict direct tile copying to single-tile images
merge develop -D org -I include -E exclude: PR 528 (Tile performance improvements for VMS and NDPI)
merge develop -D org -I include -E exclude: PR 857 (Initial support for Zeiss .lms files)
merge develop -D org -I include -E exclude: PR 858 (Initial support for Veeco AFM data)
merge develop -D org -I include -E exclude: PR 859 (Assorted metadata/tile parsing fixes)
merge develop -D org -I include -E exclude: PR 866 (Update POMs to point to mirror of the cppwrap plugin (rebased onto develop))
merge develop -D org -I include -E exclude: PR 884 (Make a buildable source release)
merge develop -D org -I include -E exclude: PR 885 (Correctly set Modulo annotations for multi-Image datasets)
merge develop -D org -I include -E exclude: PR 886 (Flex: be more permissive in parsing IFDs and XML)
merge develop -D org -I include -E exclude: PR 891 (Fix tiled TIFF reading and writing (rebased onto develop))