make issues for the TRAC issues.

[kohlhase]

It would be good to have the old TRAC issues mixed in with the ones here. I have cleaned up the old TRAC issues a bit, here is the rest: https://trac.mathweb.org/planetary/query?status=accepted&status=assigned&status=new&status=reopened&component=PantaRhei&col=id&col=summary&col=component&col=status&col=type&col=priority&col=milestone&order=priority
For every one of those, we should have an issue with the same title (or improved) and a brief description (adapted to the new situation) and a reference (TRAC URL)to the old issue (which should be closed with a note referencing the github issue).

This would give us more overview in planning.