tests with make3dgal help find effective r_s for inclined thick disks

producing 3d flux densities with Bessel functions following Spergel
2010 and producing projected images at different inclinations, results
suggest that effective scale radius can reasonably be approximated as
ry' = ry * sqrt[1 - sin(inc)**2 * (1 - (rz/ry)**2)] where ry=rx is the
scale radius for the face-on disk and rz is the disk thickness. The
approximation doesn't seem as good for face-on thin disks (Bessel
profiles appear less cuspy than exponential) and it hasn't been tested
for different values of nu, which approximate different Sersic
indices.

Continuing work on #8