Breaking: #59659 - Removal of deprecated code in sysext backend 

Flexforms 

Flexform xml that still contains the old "<tx_templavoila><title>" code has to be adapted. The "<tx_templavoila>" elements needs to be removed.

Wizard registration 

Wizard registration in TCA must not contain the "script=some/path/script.php" definition anymore. The new API for registering wizards is to set "module[name]=module_name".

Removed PHP methods 

• AbstractRecordList::writeBottom() is removed without replacement. The functionality is not needed anymore.
• SpriteGenerator::setOmmitSpriteNameInIconName() is removed in favor of setOmitSpriteNameInIconName()
• DocumentTemplate::isCMlayers() is removed without replacement. The functionality is obsolete.
• DocumentTemplate::getFileheader() is removed. Use getResourceHeader() instead.
• BackendUtility::displayWarningMessages() is removed without replacement. The functionality was moved to ext:aboutmodules.
• IconUtility::getIconImage() is removed without replacement. Use sprite icon API instead.
• PageLayoutView::getSelectedBackendLayoutUid() is removed. Use BackendLayoutView::getSelectedCombinedIdentifier() instead.
• ClickMenu::menuItemsForClickMenu() is removed without replacement. The functionality is obsolete.

Removed JS functions 

• showClickmenu_noajax() is removed. Use Clickmenu.ajax = false; showClickmenu_raw(); instead.
• setLayerObj() is replaced with Clickmenu.populateData().
• hideEmpty() is replaced with Clickmenu.hideAll().
• hideSpecific() is replaced with Clickmenu.hide(). E.g. Clickmenu.hide('contentMenu1');
• showHideSelectorBoxes() is replaced with toggleSelectorBoxes().