Quaternion: Axis and Real constructor.
Quaternion: Copy constructor.
Quaternion: Using Vector4 and Scalar for axis/real
Quaternion: Compound assignment operators
Quaternion: Operators return copies, not constrefs
Quaternion: Operator implementations.
Quaternion: Add Length and LengthSq methods
Quaternion: Normalize and Normalized implementations
Quaternion: Add unary operator-
Quaternion: Invert and Inverted implementations
Matrix: Add new constructor with all 16 values
Quaternion: Add GetAxis/Angle methods
Quaternion: Add ToMatrix method
Quaternion: Add FromEulerAngles static method
Vector4: operator= now copies 4th coord
Quaternion: Renaming components
Axis and Angle are incorrect - the components do not represent the actual
axis and angle of the rotation by themselves.
Quaternion: Add FromAxisAndAngle static method
Quaternion: Formatting fixes