Deprecation: #64068 - Deprecate thumbs.php and ThumbnailView

See forge#64068

Description

Prior to the File Abstraction Layer (FAL) there was typo3/thumbs.php generating all preview images for the TYPO3 Backend resources. This functionality is now marked for removal in TYPO3 CMS 8, as all functionality in the core already uses the File Abstraction Layer.

Impact

Using ThumbnailView, thumbs.php or BackendUtility::getThumbNail() will throw a deprecation warning.

Affected installations

Any TYPO3 installation with custom extensions using one of the files / methods mentioned.

Migration

Use the File Abstraction Layer for any custom works. See BackendUtility::thumbCode() for inspiration.