Reverse geocoding functionality

It is sometimes useful to have reverse geocoding lookup as well as address search.

The 'reverseLookup' option switches on the reverse geocoding lookup feature, while 'showAddressTooltip' makes direct and reverse geocoding result visible as a tooltip for the marker.

The new 'geosearch_foundaddresses' event is available for the map additionally as a result of reverse geocoding lookup.

The geosearch_showlocation event happens for the reverse lookup as well.

Three major providers has reverse lookup option now. Others are address-search only.