Remove redundant code in SVG point-and-click

The "hover" and "setcursor" actions had quite redundant code which is now
in a dedicated function.
I can imagine that there will be more merging possibilities available with the
PDF point-and-click code, but didn't look into that so far
Saving initial position, getting rounded difference and adjusting to it
Merge branch 'svg-pac' of https://github.com/PeterBjuhr/frescobaldi into svg-edit