Remove block Course Overview as required

[Info 3bits]

From moodle 3.3 Course Overview is not included and should be replaced as required by the needed code.

It is a blocker for moodle 3.3 because shows blank screen after upgrade moodle.

[Jeremy Hopkins]

I think the best thing would be to remove this functionality entirely then. Most people do not even know it exists within the theme and if the block is being removed from the default it is unlikely to continue being used.

Do you think that is the best approach or would you try to retain it for older versions?

[Manoj Solanki]

Fix #659 to remove any reference to using course overview block in navigation menu.

→ <<cset dabc789b8739>>

[Manoj Solanki]

Also tested on current 3.3 dev version and no issues found.