don't remove iframe in lightbox when closing

fixes problems with youtube component (which also creates an iframe)

if you need to do that, create your own javascript for the component and remove/re-add the iframe there
Merge remote-tracking branch 'github/3.7' into 3.7
lightbox fires hide and show events for onElementShow/hide functions
youtube works now with hide and show support for lightbox

on hide it will paused and on show it will be replayed if autoplay is on
Throw events when hasVisible is true, not false
names legacy headlines trl form correctly
fixed double headline rows in table for trl

split dataRows and added headRows - same as master