[Proj] +axis switch to control axis orientation

[Gerald I. Evenden]

My first reaction to the thread was to simply add the basic transformation 
matrix to the xy side of the proj system but after looking at

http://en.wikipedia.org/wiki/Transformation_matrix

I think the more general affine matrix would be a better final solution.

+xform=[comma separated array of 4 or 6 real numbers]

4 for transform, 6 for affine.

Note that cos/sin values must be precomputed.

I'm somewhat kidding about the affine. ;-)

-- 
The whole religious complexion of the modern world is due
to the absence from Jerusalem of a lunatic asylum.
-- Havelock Ellis (1859-1939) British psychologist