DXF export: fix incorrect export of polygons having thick outline (like zones): Thick segments of outline were drawn like lines with no thickness.
Fix ( workaround only) crash (Windows only) when a quasi modal frame (like footprint viewer) was called from a dialog (like the component properties dialog in schematic editor).
Very minor other fixes.
Made the project default text size apply to all text things in eeschema, instead of the hardcoded value