Lyon seems sensitive to overflow on large coordinates, so passing
twips resulting in overflow panics on very large shapes.
Avoid panics on tessellation failure: instead, return an empty
mesh and log an error.
Switch from pixels to twips for internal calculations. swf crate
was updated to add a Twips wrapper-type. Ruffle will use this type
internally for transforms and shapes. This fixes some precision
errors in rendering (see heroes_of_cybertron.swf) and will match
what the Flash Player does internally more closely. (e.g.
DisplayObject x and y will be quantized to 1/20 pixel units). It
is up to the renderer to convert units from twip space to pixels
when rendering.
Mike Welsh