added raycasting of pointclouds with BufferGeometry

added optional parameter intersectPoint to Ray.distanceToPoint()

fixed Ray.distanceToPoint()
Add methods .merge and .makegroups
added raycasting pointcloud example. fixed raycasting issues.

fixed example
Merge remote-tracking branch 'm-schuetz/dev_raycasting_pointclouds' into dev
Spaces clean up.
More clean up.
Updated builds.
Merge pull request #4787 from paulmasson/patch-1

Add methods .merge and .makeGroups
Moved Raycaster's Sprite code to Sprite.raycast(). See #3492.
Updated builds.
Added raycast() method to Object3D.
Fix array overflow in Raycaster.intersectObject for indexless buffergeometry
Also removes unused offsets var.