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.
Fix headers as per JM's suggestion
Merge pull request #971 from sbesson/10384_thumbnails

OMERO.matlab: add function to retrieve thumbnails (see #10384)