This commit adds a set of templates for the calendar month block, and
the events filter. The same data exporters used in the main calendar
view are utilised and the same logic.

Some additional data was added to the exporters, and in the long term
this will be used in the main monthly view so I did not feel it was
prudent to strip it out into a different view of the model.

AMOS BEGIN
 MOV [monthnext,access],[monthnext,calendar]
AMOS END

This class was present in clean/more but was forgotted in boost

My solution is to remove the padding that's added within scss/bootstrap/_navbar.scss (line 72)
for the case that a logo (has-logo) is uploaded and displayed within the navbar.
Removing this padding will center the image within the navbar.

* Set custom-select elements with a maximum width of 100% of their
container.

- Accessible info tables
- Outcome icons
- Navigation bar for missing contexts
- Heading contents standarisation

We have a way to determine a valid zindex when adding things to a page. Find all the moodle-has-zindex things and
choose a value bigger all of them. This needs doing in javascript whenever a thing is opened. It's not possible to
fix generically in CSS (remember the historic z-index wars).

Revert "MDL-59382 theme: bring the date picker forward"

This reverts commit 63dd7522.

We want to avoid page jumps wherever possible. This change uses the original select element as a "proxy" to reserve the space
in the DOM for the enhanced auto-complete when the JS runs.

It uses visibility: hidden to make the select not rendered - but still take up space.

The exact sizing for the CSS was determined by testing and reverse engineering the bootstrap calculations.

The size of user pictures in selectors was reduced to avoid flicker when switching between no selection and a selected user. I
could have reserved a larger amount of space, but it looks worse for pickers with no pictures.

Instead of putting vertical-align: middle as indication for participants table
headers, none is set which leads to theme default, i.e. bottom in Clean and Boost.

This causes parts of the pagination bar to show through overlays and modals.

Revert the change I made in MDL-59382 to correctly set the id for inline
form elements because it's breaking a bunch of different places that had
already worked around the problem.

It's impossible to gain the right colour contrast against a dark footer
using the same primary colour that gets 4.5 against white.

We have to choose a colour that is 4.5:1 against white and 3:1 against
the text colour. I darkened the link colour somewhat and darkened the
text colour

Part of MDL-59313.

Part of MDL-59313.