* add call to ButtonFactory::MakeIconLink
* add some CSS customizations to h1, h2, HR
* add H2 with id to link to specific regions
* add @link PHPDoc in related components
* fix typo in alerts (title was using "alert" instead of "panel")
* Fix TWIG exceptions due non existent JS templates for ajax tab
* Fix DisplayBlock::GetRenderContent and HistoryBlock::GetRenderContent signature mismatch warning
* Add return type hinting on ButtonFactory methods
* Rename ButtonFactory::MakeAlternativeNeutralActionButton() to ButtonFactory::MakeLinkNeutral()
* Add ButtonFactory::MakeLinkNeutral() to visual test page
* Fix button spacing/padding when only icon or label