------------------------------------------------------------------------
Cone and clock angles (alpha,delta) to inertial quaternion.

delta is defined with respect to the osculating orbital plane, where
k_hat is the unit vector orbit normal.
The sail normal is defined along the X axis in the body frame.
n = (cos alpha) r_hat + (sin alpha sin delta) theta_hat + (sin alpha cos delta) k_hat

When the angles are zero, then
n_hat = r_hat = Xbody
theta_hat = Ybody
k_hat = Zbody

Since version 7.
------------------------------------------------------------------------
Form:
[alpha, delta] = QToAlphaDelta( q, x )
------------------------------------------------------------------------

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Inputs
------
q      (4,1)   Inertial quaternion in the solar ecliptic frame
x      (6,1)   [r;v] Cartesian state

-------
Outputs
-------
alpha  (1,1)   Cone angle
delta  (1,1)   Clock angle

------------------------------------------------------------------------
Reference: Bong Wie, Propellantless AOCS Design for a 160-m, 450-kg
Sailcraft of the Solar Polar Imager Mission, AIAA 2005-3928, p. 11
------------------------------------------------------------------------

## Children:

Common: Quaternion/QTForm
Math: Linear/Cross
Math: Linear/Unit