Fix for "freckles" generated by the Autorouter preventing the Miter
optimising function to work properly.

The autorouter creates tiny traces (so called "Freckles") that are
incompatible with the trace optimiser Mitering function.

The following patch extends the trace optimiser "simple" optimization
function to remove the overhangs.
This means that mitering becomes possible by performing
"trace optimiser -> simple optimisations" after autorouting operations.

Reported-by: eschabor

Signed-off-by: Bert Timmerman <bert.timmerman@xs4all.nl>