While trying to use /trace_route for a recorded pedestrian GPS track along a section of the John Muir Trail in CA, the output included a large erroneous segment of doubling back that did not reflect any component of the track. The GPS data itself is fairly clean and doesn't reverse its course, and simply heads continuously south along the trail. But in the routed geometry, at a point near an i

TilePix only supports orthogonal maps (currently - hopefully we'll be able to support other types in the future). A sensible error should be returned on Reading a map which doesn't have orientation="orthogonal".

Need to set up a constant for each type:

• orthogonal
• hexagonal
• isometric
• staggered

Then, using a switch statement, check against each, returning an error if not