AZMED reprojection snaps X within 30cm of X origin to origin

[ravenAtSafe]

The value of cs_AnglTest is such that X values within ~30cm of the X origin (center of AZMED/AZMEA system) get snapped to 0 during dynamic reprojections.

CS_azmed.c:

   /* Tmp3 and sin_del_lng will both be zero if the
      point is the origin.  Most atan2's (not all) will
      bomb if both args are zero. */

   if (fabs (sin_del_lng) > cs_AnglTest)
   {
      Az = atan2 (sin_del_lng,tmp3);
      sin_Az = sin (Az);
      cos_Az = cos (Az);
   }
   else
   {
      /* del_lng is zero, we do a quick and
         dirty atan2. */
      [...]

[Norm Olsen]

Changed the threshold for filtering out calls to atan2 when both arguments are dangerously close to zero, such as when converting a point very very close to the origin of the coordinate reference system. New value is 1.0E-12, about 6 microns on the surface of the earth.

Submission produced version 2461.