[GCAD] Ensured that all :Set () methods return self.
[GCAD] Added EulerAngle and UnpackedEulerAngle classes.
[GCAD] Added Matrix3x3:Rotate () and Matrix3x3:RotateUnpacked ().
[GCAD] Renamed Matrix3x3:Scale () to Matrix3x3:ScaleUnpacked ().
[GCAD] Added Matrix3x3:Scale ().
[GCAD] Added RealFIRFIlter and RealIIRFilter classes.