• Increase size of trailing mark

Summary:
On HiDPI screens and/or usage of small fonts current size of marker is
so small making it almost invisible, even with a saturated color choice.
This is specially visible on darker themes.

Reviewers: mwolff, kfunk, cullmann

Reviewed By: cullmann

Subscribers: cullmann, anthonyfieroni, dhaumann, sars, Frameworks

Tags: Kate, Frameworks

Differential Revision: https://phabricator.kde.org/D7884