Merge 2.4 into master

Original pull requests:

* #2434 from Nerei:viz_continue
* #2462 from ibtaylor:fix_deblurring_calcBlurriness_var_name_typo
* #2475 from ilya-lavrenov:ocl_2.4_fix
* #2484 from berak:mat_doc_24
* #2485 from Nerei:viz_correct_viewer_pose