Example for obtaining a Google base map

By simply defining the ol3 map as control on a GMaps map, we can
have a Google base map with arbitrary ol3 content on top. This
works with all ol3 renderers.
Updating example to use the new vector API
Merge pull request #1421 from ahocevar/google-integration

Example for obtaining a Google base map
The examples don't provide information on classes used
Create styles only once
Merge pull request #1646 from tschaub/example-index

Remove unused classes info.
Merge pull request #1647 from openlayers/style-

Create styles only once
Fix vector examples
Merge pull request #1648 from elemoine/1648

Vector examples are broken
Assert that an element is removed in ol.structs.RBush#remove_
Fix test description
Replace faulty iterative ol.structs.RBush#remove with less faulty recursive version
Return, and check, boolean value from ol.structs.RBush#remove indicating whether value was removed
Move remove from ol.structs.RBush to ol.structs.RBushNode
Icon images are handled by a separate class
Fix the kml format tests
Vector renderer uses new image style interface
Vector image source uses new image style interface
Introduce an icon image cache
Use the icon image cache