improvement on mouse dragging
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
Initial stub of an object editor

This will be developed along with the SVG editing functionality
but probably won't be restricted to it.

Independently from graphical editing features this is intended to serve as
a UI to insert and edit tweaks and overrides.
reset variable for saving initial position
Merge branch 'svg-edit' of https://github.com/PeterBjuhr/frescobaldi into svg-edit
Write offset in Object Editor
change color when element has been changed
Avoid swapping object when dragging
button to reload current document
Check before changing color
Very basic save SVG feature for development purposes.
Clean before save prepared
Better wording in comments
Use signal-slot for object editor updating WIP

This is a first working implementation that should very much be
cleaned up.
Anyway the SVG view now emits a PyQt signal, and the Object Editor
connects to that to update the spin boxes.
Calculate offset while dragging.
Merge branch 'svg-edit' of https://github.com/PeterBjuhr/frescobaldi into svg-edit
Calculate offset in calcOffset to avoid zooming error
Start reorganizing Object Editor's slot mechanism

The Object Editor will have to manage its connections to the SVG view
(and the editor?) dynamically. That is, when it is hidden it should disconnect
from the signals from the SVG viewer.