Bump threshold for Orthogonalize to 12 degrees

To finally address https://github.com/openstreetmap/iD/issues/1902  I talked to @jfirebaugh about this a while ago, so finally pushing through the change.

Basically the "square" action only tries to square or straighten nodes that are within a certain threshold. It leaves the others untouched. This PR changes the threshold from 7 -> 12 degrees.