Customizable links on home and footer

[eilmiv]

Summary of changes

Configurable arbitrary links

• in footer
• as boxes on home screen including some icon or logo
• extended funder logos on footer and about/us by option to only show logo in either place
  • e.g. to have the dark version of a logo in the footer while the light version is on the about/us page
  • e.g. to only have logo on about/us page if there are too many

Also adds an html id attribute to the sections on the screen where it is still missing.

Motivation and context

Part of mTeSS-x project to allow further customization of different instances. (In particular relevant for PaN Training to allow imprint link in footer and links to wiki and e-learning on home.)

Screenshots

The example contains the configured links "Access Courses", "PaN Wiki" and "Test":

The example contains the configured links "Imprint" and "Test"

Checklist

• I have read and followed the CONTRIBUTING guide.
• I confirm that I have the authority necessary to make this contribution on behalf of its copyright owner and agree
  to license it to the TeSS codebase under the
  BSD license.

[eilmiv]

This may be a controversial choice to reuse the catalogue css classes for the additional links.

[fbacall]

I think it's OK, unless you can think of a better name for the CSS class that applies to both uses...

[eilmiv]

I couldn't think of a better name, instead I added an extra class which allows more intuitive theming separate from the catalogue feature.

[fbacall]

Looks good, but could you add a test with each one of the settings used?

See test/controllers/static_controller_test.rb for examples

[fbacall]

I think it's OK, unless you can think of a better name for the CSS class that applies to both uses...