1D minimization additions and doc comment

[Jeff Spirko <spirko at Topquark dot physics dot lehigh dot edu>]

I threw together functions for accessing the values of the function
being minimized, which are stored in the minimizer structure.  I
also included a doc string for the functions (check this).  It
seemed cleaner to do it this way than to access the structure
myself.  A patch is attached, referenced to gsl-1.1.1.  Please TEST
the code, I haven't yet. :-(

Also, the use of the terms x_lower, x_upper, and minimum in the docs
caused me to look at the source code to make sure that minimum
wasn't really f_minimum.  Maybe it should be called x_min instead?
Earlier in the Overview section these variables are referred to as
a, b, and x, though I'd prefer the longer names for the code.  Maybe
there should be a sentence relating the two sets of names.

-- 
Jeff Spirko   spirko@lehigh.edu   spirko@yahoo.com   WD3V

The study of non-linear physics is like the study of non-elephant biology.

All theoretical chemistry is really physics;
and all theoretical chemists know it. -- Richard P. Feynman

Attachment: min_f_vals.patch
Description: C program text