cut down on false positives

[tcql]

There are currently a lot of false positives. Some are difficult to handle automatically, such as trails that run along a road but are definitely not acting as sidewalks.

Others would be more simple to handle, such as:

• footways that explicitly have surface other than paved that indicates that it is unpaved
• if there are two footways parallel to a road on the same time, the innermost may be a sidewalk, but the outermost is not

In Germany (and other areas), sidewalks are typically not drawn separately from road ways, but instead tagged on the road with sidewalk=left/right/both. This means that most candidate sidewalks in Germany are probably false positive, so once we have global runs up, we should work on reducing these errors