By adding a getTileCoordForTileUrlFuction method like for ol.source.Tile,
we can now properly handle extent and resolution restrictions, and reuse
tiles on wrapped worlds. Also adds the missing wrapX option to
ol.source.TileVector.
ol.layer.Vector can now manage both an RTree and a Collection of features.
The new useSpatialIndex option allows to opt out of RTree management, and
the new ol.Collection type of the features option allows to opt in for
Collection management.
The addition of full extent tile ranges also allows us to simplify wrapX
handling for tile layers. By limiting wrapX to true and false as possible
values, we can remove a lot of guessing logic.
Added functionality to create a wmts tilegrid and wmts source from the
capabilities object created from ol.format.WMTSCapabilities.read().
Added tests for these functions and an example.
Also altered the REST url template replacement to be case insensitive
and added tests for this. This is because the spec uses both style
and Style and both of these are used by existing WMTS services.
Most of our uses of source extent were cargo cult programming. The source extent was seldom and inconsistently used. Instead, layers can now be configured with an extent, and layer renderers limit rendering (and data requests) to the layer extent.
For vector sources, the `getExtent` method returns the extent of currently loaded features (this was the case before and after this change). For tile based sources, we will likely want to allow easy construction of tile grids based on an extent (this is not possible before or after this change, but could be added later).
Tile grids cannot currently be constructed with an extent (though we should perhaps provide a function that allows this - see 68815dca10 for an example).
