Add all points of the edges to the path.

Add unit tests.

Don't limit the distance when finding the graph entry
and exit points, start/goal can be arbitrarily far away
from the graph.

Always return PathfinderResult, also in private
functions.

If the graph entry (closest vertex to start location) is closer
to the graph exit (closest vertex to the goal location) than the
range, the GraphPathfinder can't generate a useful path.

Return goalNodeInvalid == true in this case and log an error.

An edge with a single vertex results in an
infinite loop.

Also turned off GraphPathfinder tracing.