Adoption or new type for <tAngleDeg>

Currently there is the type defined allowing values from -360 to +360 degrees inclusively. It is (at least) used in infrastructure part for the angle of level crossings. In rolling stock part the phase angle shall be now given in degree instead as cosinus value. This would require a range from -180 to +180 degrees inclusively. Thus the actual type can be used. However, it might be useful to derive a new type or adopt the existing one accordingly.