- fix an error if there is no group selected
Contao 3 compatibility
CS, updated copyright statement
Adjusted module (inverted logic)
CS: whitespace instead of tabs
Improved runonce script, removed duplicate code
Make getContentElement static and use the same method in runonce
Import BackendUser in constructor
No need to loop through the groups, TL_PERMISSION takes care of this!
The button permissions were incorrect
CS
Fixed tl_content filtering

1: DCA was not closed when no elements were available
2: Access permission was not working (due to inverted logic)
Fixed sorting of elements in the clipboard (#1)
Merge branch 'release/2.0.0'