Suppressed a warning in AppDelegate

Warnings 0169 and 0414 are false-positive about Framewor.App, since
that is the way the class is used.
Added local and world rotation to Transform.
Added Sign and ClampAngle methods to Mathf.Common.

Sign is the same as Math.Sign, but with a float or an int. ClampAngle
clamps the given value between -180 and 180, by making sure the actual
angle stays the same.
Added Transform.Rotate and fixed bugs in the rotation matrix.