place/point/add - Adds a new point to a place.

Method parameters:
id - The ID of the place to add the point to.
latitude - The latitude of the point.
longitude - The longitude of the point.
altitude - The altitude of the point.

Returns a JSON document of the following format:
<number> - The ID of the newly added point.

Expected errors:
PLACE_NOT_FOUND - A place with the ID doesn't exist.