Followup to https://github.com/flarum/core/pull/2524.
In that PR, we fixed infinite scroll for the panel, but accidentially used document.body. Since scrollTop on body is (almost always) 0, this means that new pages of notifications were loaded on every scroll, which quickly becomes overwhelming. Instead, we can use `document.documentElement` for getting scrollTop, which results in the expected behavior.
* Don't update scrubber while post pages loading
This alleviates the scrubber bouncing around when scrolling up on iOS
* Throttle loadMore loadPrevious
Throttle loadMore and loadPrevious functions to alleviate skipping over pages and pages of posts during one scroll. This sometimes happens on iOS
Adds a rule to the discussion list less file which targets touch devices whose primary way of interacting does not include a mouse / ability to hover. For those devices the toggle button is hidden which fixes the double tap issue.
It can be very annoying if we want to use something like boolval, but have to define an entire anonymous function to pass it in. This PR adds support for tpassing it in directly as a string, like is posible with User::registerPreference.
Model Visibility extender does not take into consideration missing
dependencies. For instance flarum/tags adds a policy on the Flag model
from flarum/flags. But because flarum/flags might as well not be
installed we need to check for the existence of that model. Otherwise
the exception is thrown or flarum fails to boot.
Since some boolean settings might be stored as string "0" or "1", the previous system no longer works, and it always sets the switch to true. The "no setting" check has been changed to reference `undefined`, so now the switch will only be defaulted to `true` if the setting truly hasn't been set.
Fixes https://github.com/flarum/core/issues/2574
Improves calculations for determining whether we are at the bottom of the notifications panel (which would trigger infinite scroll). This should be particularly effective in fixing issues on smaller screens.
