Author: Jason Fowler
MDL-32946 - Blocks - Improving image alts for accessibility.
http://git.moodle.org/gw?p=moodle.git;a=commit;h=473327030e370569116a2018f4b05ce10cdd6dac
http://github.com/moodle/moodle/commit/473327030e370569116a2018f4b05ce10cdd6dac
+ 2.5 en [dockblock,core_block]