Currently if users enabled the "Treat ellipses and splines as polylines"
option in DXF export preferences and exported them, they were still
being exported as native primitives.
This was because we were reading from a wrong preferences location, UI
stored it in `BaseApp/Preferences/Mod/Draft`, but it was read from
`BaseApp/Preferences/Mod/Import`. Since the pref didn't exist, we were
taking default value which was set to `false`.
So the solution is obvious - just set it to the correct path.
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