Merge MOODLE_310_STABLE branch

[TomoTsuyuki]

Merge the latest code to the coursemode branch

admin/tool/crawler (coursemode)$ git merge MOODLE_310_STABLE 
Auto-merging classes/robot/crawler.php
CONFLICT (content): Merge conflict in classes/robot/crawler.php
Auto-merging cli/crawler.php
Auto-merging lang/en/tool_crawler.php
Auto-merging lib.php
CONFLICT (content): Merge conflict in lib.php
Auto-merging locallib.php
CONFLICT (content): Merge conflict in locallib.php
Auto-merging settings.php
Auto-merging tests/phpunit/robot_cleanup_test.php
Auto-merging tests/phpunit/robot_crawler_test.php
Auto-merging version.php
CONFLICT (content): Merge conflict in version.php
Automatic merge failed; fix conflicts and then commit the result.

[vithushau]

Thanks @TomoTsuyuki LGTM