Add topological operation on locations
Update track procedures

- Relative Extremity :: extremity on a segment relatively to another segment
- End of Route :: to the last linked segment
Add Oriented Location, that are location + a toward extremity element
Replace generic topo with access constant to track so it follows track dynamics
Add Switch Is_Set function to avoid having to catch exceptions
Avoid using exception in normal procedure executions. Use guard functions
Topology of oriented point depends on point orientation if no reference segment is given

(rather than absolute orientation of segment of the point)
Avoid depending on exceptions
Circular test track to test topologic functions (+, -, <)
In development, add every statics and dynamic checks