Add caching for navigation bar

[Jeremy Hopkins]

There is a lot of code used to generate the navigation bar which hase become more complex / expensive since adding options to sort past and present courses.

We should add caching for the entire navbar to reduce risk of performance issues.

This should be extended to replace the previous method of using session variables for other menus, and cache the entire user navigation.

[Jeremy Hopkins]

Fix #362 adding caching for navigation bar

→ <<cset 0d4908fc1ed7>>

[Jeremy Hopkins]

Also see commit 1bc8bdc where more changes were made

[Jeremy Hopkins]

Fix #362 adding caching for navigation bar

→ <<cset 0d4908fc1ed7>>

[sali]

Hello,

I was having a problem where my "This course" drop down menu option seemed to have "disappeared" from the Navbar after the last update and saving a change to the Header Navbar options. After much checking I came to report it here and saw this post.

Then I tested with changing the value from 20 and only when it's 0 the "This course" option re-appears.

I'm not sure how the caching value is supposed to work and whether the changes would be immediate when made e.g. turning the option to display "This course" on/off.

I've had to set the value to 0 in order for the option to be displayed but I'm not sure if this is the correct way for the setting to be used. Kindly advise.

Thank you, sali