Closes #4087

Issue #4078

Store the modifier in the original mouse event to choose between
move and copy drags.

Issue #2556

So that they don't interfere with clicking and dragging

Issue #2556

Closes #4042

It breaks document tree rebalancing.

Closes #4032

Issue #3983

Closes #4030
Closes #4031

To make it clearer that they are updated together

Issue #4028

Closes #3983

Closes #745

Issue #2901

Issue #4022

Closes #3998

* \x1a-\x1f were missing though it looks like the intention was to cover all below \x20 (space)
* added \x7f which is usually considered non-printable
* removed \t which was already covered in \x00-\x19 as \x09

Issue #3979

See https://discuss.codemirror.net/t/drag-drop-modifiers/721

Closes #3958

Issue #3956

5.13.4 was a trivial release restoring a LICENSE file.

Closes #3905

Issue #3884

Issue #3884

Closes #3899