Some more flat event monadification

Signed-off-by: Christoph Höger <christoph.hoeger@tu-berlin.de>
Make relation signaling depend on the index rather then the handle

Signed-off-by: Christoph Höger <christoph.hoeger@tu-berlin.de>
Add a root-found method

Signed-off-by: Christoph Höger <christoph.hoeger@tu-berlin.de>