Add utility function to create a ThumbnailStore and set pixels id
Add function to retrieve the thumbnail of a given image
Add function to retrieve thumbnail by longest side
Fix toMatlabList() for ArrayLists with one element

- Add tests for single-element array lists conversion
Remove getThumbnailStore() and fix functions to read thumbnails
Add method to retrieve thumbnail set from a series of input images
Add 2d method to retrieve thumbnail set from a series of input images
Improve thumbnail size validation function
Preserve mapping between pixels id and thumbnail when retrieving set

Return structure array with three fields: thumbnail, pixels and image.
Fix image input validation in getThumbnail*() methods
Re-initialize thumbnail service for each series of 50 thumbnails
Add MAX_RETRIEVAL constant to specify maximum number of thumbnails
Handle case where not thumbnail is read in getThumbnail*Set() methods

If byteArray is empty, the thumbnail field of the corresponding element is
filled with an empty array.
Revert "Change error responses to 404 in query API"

This reverts commit 1f3f8d1354444445a23c337be315252c156b9e01.

Per suggestion from will-moore, removing 404 responses from AJAX calls
and returning a dictionary with an error field instead.
Fix headers as per JM's suggestion
Merge pull request #1008 from snoopycrimecop/merge/dev_4_4/submodules

Update dev_4_4 submodules
Merge pull request #971 from sbesson/10384_thumbnails

OMERO.matlab: add function to retrieve thumbnails (see #10384)
Merge pull request #1007 from knabar/dev_4_4

Revert "Change error responses to 404 in query API"
Update submodules