MDL-46816 mod_asssign plagiarism: Remove unnecessary code.
MDL-46753 auth_cas: Replace hardcoded logout_return_url to user defined URL.

Credit goes to Mitsuru Udagawa, thanks!
MDL-46842: Reopen assignment submissions when using offline grading worksheet
MDL-46477 chat:hard coded string in mod/chat
Merge branch 'm26_MDL-46816' of https://github.com/danmarsden/moodle into MOODLE_26_STABLE
Merge branch 'm26_MDL-46842' of https://github.com/greg-or/moodle-mod_assign into MOODLE_26_STABLE
Merge branch 'MDL-46753-26' of git://github.com/lameze/moodle into MOODLE_26_STABLE
Merge branch 'MDL-46477_m26' of https://github.com/shashirepo/moodle into MOODLE_26_STABLE
MDL-46842 assign: Fix for unit tests - previous patch was completely ignoring manually reopening attempts.