Enhancement: Re-kern option when changing fonts.

The attached file is an original EPS I was supplied with (seemingly under the terms of the UK Open Government License). When converted/inported in Inkscape, a font substitution is made, but the text is not necessarily re-kerned for the new font.

This means that I've had to do a semi-manual removal of manual kernings, and font substitution.. On a simple diagram like this it's quick to do. But on a more complex one it's rather time consuming.

It would be nice to have an option when doing the import to remove "manual kerning" caused by the font substitutions automatically during the import process, and a preference to remove it when changing fonts using the toolbar.

I will be posting the imported SVG (and my attempted cleanup in subsequent comments.)

(BTW I am strongly suspecting that the unsual combination of some text/tspan elements is an aspect of the original EPS and not necessarily an issue with the EPS->PDF-Inkkscape importation process. However if anyone wants to look into this in more detail they are welcome to... )