test link speeds

test that the ration between speeds of links and their corresponding way type are reasonable. each test checks that it's:

- faster to follow a main way of length 5 than a link of length 3
- slower to follow a main way of length 7 than a link of length 3

the lengths above is simply the distance of the way sections in the tests. from this it follows that:

5*linkspeed < 3*mainspeed < 7*linkspeed    =>
1.66*linkspeed < mainspeed < 2.33*linkspeed

ie. the speed of main way must be between 1.66 and 2.33 times the speed of the link.