Avoid touching the geolocation object until needed

IE9 leaks when `navigator.geolocation` is accessed (see #461).  The goal of this change is to avoid that leak in builds that include the Geolocate control but do not use it.
Merge pull request #461 from tschaub/ie9-leaks

OpenLayers-2.12-rc2 + jQuery-1.7.2 Memory leak in Internet Explorer 9 (p=@tschaub,r=@marcjansen,@elemoine)
Simplifying layer visibility handling

Instead of adding and removing the Google container, we just toggle
style.display. This also removes the unused rendered and displayed
properties of the cache.
Merge pull request #925 from ahocevar/google-container

Google Maps rendering bug on fresh reload. r=@kevbradwick (fix #925)
Explicitly require the various Geometry types, as in GML.js, so listing OpenLayers/Format/WKT.js in a build config file is sufficient to build in these types.
Merge pull request #532 from adv-isu/WKTrequires

Format/WKT.js: add @requires for geometry types
Also trigger beforefeaturemodified event in non-standalone mode

d2a32d5 accidently changed the number of assertions in the
test_selectFeature function, so the change in behavior that no
beforefeaturemodified event is called any more in non-standalone mode got
unnoticed: Before unhacking ModifyFeature, the SelectFeature control
called the beforeSelectFeature method directly. Now, without a built-in
SelectFeature control, we need to call it from the selectFeature method in
both standalone and non-standalone mode.
Merge pull request #931 from ahocevar/beforefeaturemodified

Also trigger beforefeaturemodified event in non-standalone mode. r=@bartvde
Documentation improvement (fixes #932)
Another documentation improvement for #932.
Yet another documentation improvement for #932.

Now it should be clear that the map's changelayer event is triggered
whenever the layer's actual visibility (i.e. visible to the user) changes.