clean up EdgeMatcher

Signed-off-by: Anurag Priyam <anurag08priyam@gmail.com>
Do not activate edge matching on selected feature if no other feature
edge-matches with it.

https://github.com/GMOD/Apollo/issues/9

Signed-off-by: Anurag Priyam <anurag08priyam@gmail.com>