fix tests: add missing implementations of getImageDataOrEmptyImageData for trl
fix if no entries are in the multicheckbox

e.g. this can happen if a directory with categories is used and no category is added
added getImageDataOrEmptyImageData function for abstract image trl component
Revert "added getImageDataOrEmptyImageData function for abstract image trl component"

This reverts commit 8d669a13f5423508b2c63e4f1881c1a179563aad.
Move Events to NoAdmin because they are also needed there
Throw event only when hasVisible is set
recreate the events.php and extend from directory no admin

extending from that events.php didn't work anymore, because it got moved to directory no admin
e.g. oebsv