DXF import: fix scale of rotated ellipses

What does the merge request do?

Correct the scale of the rotated ellipse to the correct one.

(rotated ellipse size different when import dxf CAD file (patched file attached))

Closes #504 (closed)

Implementation notes

Nothing in particular.

Summary for release notes

Projected drawings such as cylinders output from CAD can be accurately reflected.

Checklist

• Add unit tests (if applicable)
• Changes to inkex/ are well documented
• Clean merge request history