[PATCH 0 of 8 v2] Move bookmarks to core. Second iteration

[David Soria Parra]

Hi,

this is the second iteration of my patch series to move bookmarks to core.

The first part moves bookmarks to core without any changes to functionality.
The second part does some code cleanup.
The third part are smaller additions and behaviour changes.

This does not include the patch to remove track.current yet. I'll bigger
behaviour changes like this in a later series.