Fixed bug: Motorways now default to being oneway unless explicitly marked bidirectional.

Signed-off-by: Ted Steiner <tsteiner2@gmail.com>
Bug fix: Highways labeled "services" are now ignored because they are not traversable highways.
(Probably these are actual services on the side of the road.)

Signed-off-by: Ted Steiner <tsteiner2@gmail.com>
Enhancement: Now only "visible" map data is loaded.
Data tagged as "visible=false" is historic data, and should not be used. This means it has been deleted from the database.

Signed-off-by: Ted Steiner <tsteiner2@gmail.com>
Bug fix: Map elements missing the visible tag are treated as "visible=true".
Some data export methods only export the visible data and therefore do not have this tag.

Signed-off-by: Ted Steiner <tsteiner2@gmail.com>
Moved all distance functions in routing to be grouped together.

Signed-off-by: Ted Steiner <tsteiner2@gmail.com>