Various Google Maps definition fixes

- Added draggable to various overlay objects
- Added `strokePosition` to `PolygonOptions`, `CircleOptions` and
`RectangleOptions`.
- Fixed `MVCArray` return and argument types for overlay objects' path
methods.
- Fixed `DrawingManagerOptions` and `DrawingControlOptions` interfaces, made
all properties optional.
- Made `GeocoderRequest.address` optional, it's not required when using a
LatLng for geocoding.
- Fixed `SteetViewPov.pitch` typo.
- Added `addListener` to `MVCObject`