evdev: if a device's rotation is around 180 degrees, flip the wheel
For a device used upside-down, make sure the wheels correspond to the new physical directions. There's a grace range of 20 degrees either way since that seems like it makes sense.
For 90 degree rotation (or 270 degree) the wheel is left as-is, the heuristics to guess what angle we want in this case is not clear enough.
See here, cc @lex_melnyk
Fixes #888 (closed)