Segment distance calculation fails when modifying points

By providing a segment even for points, we have less distinction
points between points and other geometry types, and are able to
do the segment distance calculation also for points.
Return for getFeatureInfoForPixel

In b8a9aeb14ed6089d9d676c7e8682f0db5a6d5304 a return was added to `ol.renderer.Layer.prototype.getFeatureInfoForPixel`.  The `ol.renderer.canvas.VectorLayer.prototype.getFeatureInfoForPixel` method needs the same.
Merge pull request #1311 from ahocevar/modify-points

Segment distance calculation fails when modifying points
Merge pull request #1315 from tschaub/gfi-return

Return for getFeatureInfoForPixel.