Computes the desired Hills-to-Body frame quaternion for a thruster firing.
   If called with just the first 2 inputs, the quaternion is computed without
   regard to the rotation about the thruster axis. 

   If called with all inputs, the quaternion is computed such that the star
   tracker is pointed as far away as possible from the sun, earth and moon.

   Since version 7.
   [qHB,okay] = AlignThruster( r, v, aH, bTh, bST, jD, sep, verify );

   aH              (3,1)  Unit Hills frame vector of applied acceleration
   bTh             (3,1)  Unit body vector of Hall Effect Thruster nozzle
   bST             (3,1)  Unit body vector of star tracker bore-sight
   r               (3,1)  Position in ECI at burn time  [km]
   v               (3,1)  Velocity in ECI at burn time  [km/s]
   jD               (1)   Julian Date of burn time      [JD]
   sep              (1)   Required angular separation between bore-sight and 
                           bright body horizon          [rad]

   qHB             (4,1)  Desired ECI-to-body quaternion
   okay             (1)   Boolean flag indicating whether angular separation
                           constraints were satisfield


AeroUtils: Coord/QHills
Common: Quaternion/AU2Q
Common: Quaternion/AnimQ
Common: Quaternion/QForm
Common: Quaternion/QMult
Common: Quaternion/QPose
Common: Quaternion/U2Q
Common: Time/JD2000
Math: Linear/Dot
Math: Linear/Mag
Math: Linear/Unit
SC: Ephem/MoonV1
SC: Ephem/SunV1