The UTFGrid layer's `getTileInfo` method was not correctly handling dateline wrapping (and was a bit more complicated than it needed to be). Since it would be useful to all grid layers to be able to retrieve a tile and pixel offset for any map location, this functionality deserves to be on the Grid layer.
The WMTS layer currently exposes a `getTileInfo` method that is used within the layer and by the WMTSGetFeatureInfo control. This method could be renamed to `getRemoteTileInfo` or something to differentiate it from a method that gets locally cached tile info. Until that change is made, the method on the Grid layer will be called `getGridData`.
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