Fixed issue #333 (automation of auto-measure rulers)

[klayoutmatthias]

The implementation provides a new method called "create_measure_ruler" in LayoutView:

view = RBA::LayoutView::current

# create the ruler with auto-measurement with seed point 111.8/840
ant = view.create_measure_ruler(RBA::DPoint::new(111.8, 840.0))
# style the ruler
ant.style = RBA::Annotation::StyleRuler
...
# remove the ruler
ant.delete