Merge 2.4 into master

Original pull requests:

* #2398 from nghiaho12:integral_doc
* #2406 from ilya-lavrenov:abf
* #2410 from asmorkalov:android_tiff_lowmem_fix
* #2411 from asmorkalov:android_mat_leak_fix
* #2419 from linquize:tgit.icon
* #2421 from akarsakov:fix_ocl_haar_intel
* #2433 from ilya-lavrenov:typos