Function posAngDegrees( ra1, dec1, ra2, dec2 )

Description:
Calculates the position angle between two points on the sky in degrees. The result is in the range +/-180. If point 2 is due east of point 1, the result is +90. Zero is returned if the points are coincident.
Parameters:
ra1 (floating point)
right ascension of point 1 in degrees
dec1 (floating point)
declination of point 1 in degrees
ra2 (floating point)
right ascension of point 2 in degrees
dec2 (floating point)
declination of point 2 in degrees
Return Value (floating point):
bearing in degrees of point 2 from point 1.
Signature:
double posAngDegrees(double, double, double, double)