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)
Account for the fact that touch devices have no mouse and therefore no last mouse position.  When "undo" is invoked in a mobile app, sync the meaningless last-mouse-position point to the last point in the digitized linestring so there is visible feedback that something has been undone.  Otherwise the last-mouse-position point is left at the point of the last tap on the map, which is unfortunately the location of the vertex that has just been undone, incorrectly implying that the vertex is still there.
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.
LayerSwitcher: Simplified checkRedraw() method
New example showing how to switch projections
Release notes for GPU, animated zoom and ModifyFeature control
Re-ordering topics in the release notes
Merge pull request #937 from Turbo87/layer-switcher

LayerSwitcher: Simplified checkRedraw() method
Merge pull request #927 from adv-isu/HandlerPathUndoTouchFix2

Improved touch support for Handler.Path.undo