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.
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.
Add ol.extent.extendXY
Fix order of arguments to ol.extent.createOrUpdate
Add more extent functions
Add ol.extent.extendFlatCoordinates
Add ol.extent.createOrUpdateFromFlatCoordinates
Return extent from ol.extent.extend
Add ol.extent.getArea
Add ol.extent.getEnlargedArea
Add ol.extent.getIntersectionArea
Add ol.extent.getMargin
Add optional destination argument to ol.extent.clone
Add ol.structs.RBush
Add ol.structs.RBush#assertValid
Refactor ol.structs.RBush tests
Don't check for under-full nodes when validating ol.structs.RBush

Removal can lead to under-full nodes.
Implement ol.structs.RBush#remove_
Add FIXME