Only set center and zoom if they are actually different
Make debug function global
Refactor global center and zoom setting (when 1 map changes)
Attach maps object to window for debugging
Debug logging from every map when changing center or zoom
Add zoom buttons to Yandex map
Add zoom buttons to DoubleGis map
Globalize variables holding current position (zoom, lat, lon)
Update URI when map position changes
Don't prefix 'location' with 'window.'
Update position when URI changes