Joomla 4 compatibility

[severdia]

https://docs.joomla.org/Potential_backward_compatibility_issues_in_Joomla_4

Rendering: Options for head

<jdoc:include type="head" />
<jdoc:include type="metas" /> for metadata
<jdoc:include type="styles" /> for CSS
<jdoc:include type="scripts" /> for javascript

Module Chrome
Moved to JLayout: joomla/joomla-cms#23570

Libraries
Update to jQuery v3 as default
Remove jQuery UI
Update to Bootstrap 4 as default (some BS2 classes left in to ease migration)
caption.js removed

Favicon
Joomla 4 will attempt to load template folder favicon first rather than site root

Assets
Use joomla.asset.json ?

[severdia]

Settings tabs:

[severdia]

Confirmed as working on Joomla 4 beta, but formal support will be verified when 4.0 is GA.