Moving Frame with keyboard #709

Summary of your problem or feature request

Using ctrl + track pad pan to move new frame introduces slight offsets.

Version of Sozi and other relevant software

All versions.

Steps to reproduce the problem

Add new frame, move svg by ctrl + track pad panning, ctrl doesn't prevent purely orthogonal offsets.
FEATURE: Add keyboard shortcut (left, right, up and down arrow keys), to move frame by an user provided offset.

Expected behavior

Observed behavior

Hints and solutions (optional)