Merge 2.4 into master

Original pull requests:
* #1049 from pengx17:2.4_superres_ocl
* #1077 from bitwangyaoyao:2.4_kmeans
* #1080 from hhofbaue:matchTemplate_bugfix
* #1088 from apacha:brisk_noDescriptors_fix
* #1097 from apavlenko:ocl_tests_fixes
* #1099 from asmorkalov:linux_vcap_fix
* #1102 from SpecLad:xls-updates
* #1103 from apavlenko:ver_2.4.6.1
* #1106 from pengx17:2.4_gftt_rename
* #1109 from nikman-ru:cap_reuse_24x
* #1111 from nikman-ru:fix_yamldoc