Made lib.math.angle return an angle, such that 0° <= angle < 360°.
This should not affect most calculations, but will affect anything comparing angles without using proper looping logic.
Added a new type, 'PointLike', to lib_2d. A point-like variable is convertable into a Point2d, and can be an object, map, or Point2d. This is useful for the overloaded lib.math functions.