MIAS: fix off-by-one in directory count
Imaris HDF: make the optimal tile size be more tile-shaped

...instead of being full-width strips.  The tile access time is not
really any different, but in most cases this will result in faster image
loading times.

See ticket #10272.
merge develop -D org -I include -E conflict -E needs-fixes -E broken: PR 342 (setId performance improvements)
merge develop -D org -I include -E conflict -E needs-fixes -E broken: PR 351 (Add SPW support to FakeReader)
merge develop -D org -I include -E conflict -E needs-fixes -E broken: PR 374 (Add method to retrieve the significant directory count)
merge develop -D org -I include -E conflict -E needs-fixes -E broken: PR 378 (Sprint5 bug fixes (develop))
merge develop -D org -I include -E conflict -E needs-fixes -E broken: PR 380 (Removing ndpi from readers list for fs demo)
merge develop -D org -I include -E conflict -E needs-fixes -E broken: PR 384 (Imaris HDF: make the optimal tile size be more tile-shaped)