Split gmaps.js in modules

From now on, gmaps will be separated in 15 files:
* `gmaps.controls.js`: Manage custom controls
* `gmaps.core.js`: Basic map
* `gmaps.events.js`: Manage events
* `gmaps.geofences.js`: Using geofences
* `gmaps.geometry.js`: Manage polygons: polylines, circles, rectangles and polygons
* `gmaps.layers.js`: Manage layers (Weather, Clouds, Traffic, Transit, Bicycling, Panoramio and Places) and GeoRSS/Fusion Tables
* `gmaps.map_types.js`: Manage custom map types
* `gmaps.markers.js`: Manage markers
* `gmaps.native_extensions.js`: Polyfills and internal methods
* `gmaps.overlays.js`: Manage HTML overlays
* `gmaps.routes.js`: Manage routes
* `gmaps.static.js`: Create static maps
* `gmaps.streetview.js`: Use Google Street View
* `gmaps.styles.js`: Manage custom styles
* `gmaps.utils.js`: Extra functions