Render lock gates

[pyrog]

At high zoom levels, it's difficult to see the lock when no riverbanks are mapped.

Example : lock of Picquigny

At least, render it with a circle like OSM :

If it's possible, render it with a "V" shape like this :

PS:

• at low zoom levels, only the network is rendered and the problem is similar. V shape on gates rather than lock symbols is better at my opinion because you see the lock, it's "size", how many basin it have, and the flow direction of the water.
• See also issue How to display labels for Staircase Locks ? #50.

[pyrog]

Even if riverbanks are mapped, it's difficult to see the size of the lock without gates rendered.

Example : lock of Montières

(This is a lock with 2 basins, so 3 gates, but this one is mapped with only one line with lock=yes key)