Make the `build/check-requires-timestamp` target work with namespace provides in cases where the namespace provide isn't required by a module that provides constructors or other objects within that namespace. This may seem a bit odd, but if I want to provide `foo.bar.Bam` it isn't strictly necessary that my module require `foo.bar`.
To make this build target work, we stick with the following convention (used in the Closure Library):
* If you want to make a function available via `goog.require`, use `goog.provide` to provide the object of which the function is a member (e.g. to make the `foo.bar.baz` function available, use `goog.provide('foo.bar')`).
This follows the convention in the Closure Library of providing either namespace objects (where the property starts with a lowercase letter), constructors (where the property starts with an uppercase letter), or enums (all uppercase properties, only one instance of this in the closure library).
A 'this' identifier is quite useless with compressed JavaScript,
and in fact it turned out to fail in advanced mode when trying
to access a feature's renderIntent property with it. The added
renderIntent lib function as a Call expression does the job
well.
With this change, the user provides a filter function instead of
an array of layers. Selection layers are created lazily, and
addition/removal of layers is not handled by the control to give
the user more options, as suggested by @elemoine.
I'm adding this example to demonstrate a few things that should change:
* the icon symbolizer should accept xOffset and yOffset in pixels
* the `ol.geom.Geometry.prototype.getCoordinates` method should be exported
* overlays should have a `panIntoView` method
