message: Mathlib: added Matrix2x2::Rotation function
diff: @@ -796,6 +796,18 @@ template <class T> struct Matrix2x2
  return mOut;
  }
  + static Matrix2x2 Rotation(T angleInRadians)
  + {
  + auto s = std::sin(angleInRadians);
  + auto c = std::cos(angleInRadians);
  +
  + return Matrix2x2
  + {
  + c, s,
  + -s, c
  + };
  + }
  +
  T Determinant()const
  {
  return _11*_22 - _12*_21;
  