Inkscape 0.92. incompatibilies

[depili]

The inkscape 0.92 in stretch has once again changed the handling of multiline text.
If there are both sodipodi:role=line and dy=1em attributes on a given tspan the line spacing gets all kinds of wonky.

Will probably need to bite the bullet and just split the html preview svg generation from the inkscape svg generation, or just do Something when converting from simpleslide to inkscape slide.

A hacky and dirty fix is to comment out line https://github.com/iskcrew/isk/blob/master/app/models/slides/simple_slide.rb#L218