Address various Matlab documentation issues raised by Simon (rebased onto develop)



This is the same as gh-348 but rebased onto develop.

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- Fix various typos in the Matlab documentation page
- Set default thumbnail width/height to 48 pixels
- Do not expose ``getImages(s, 'project'/'dataset', [])`` - not working in 4.4.7
- ``getObjectsXXXAnnotations(s, ids)`` does not support loaded objects yet

See #345 for original comments