[Proj] degree to radian conversions

[Charles Karney]

I just submitted a pull request for proj.4 to correct the values of the
constants used in degree/radian conversions.  The important change was
to use

   .0174532925199432958

instead of

   .0174532925199433

as the value of pi/180 used to convert degrees to radians in dmstor.c.
The new value is substantial closer to the true value...

   cos(90 * .0174532925199432958) =  6.1e-17
   cos(90 * .0174532925199433)    = -3.8e-16

Needless to say, some of the tests now fail.  Particularly because
proj.4 used to round 90 deg to an illegal latitude (larger than pi/2).

However the changes for the healpix checks are inexplicably large.

It would be good if someone could figure out why the healpix results
change so much.

   --Charles