Reading and writing GSL random number generators

[Brian Gough]

Olaf Lenz writes:
 > With gsl_rng_fprintf, the random number generator state is now output
 > in a hex-byte-by-hex-byte fashion (ae 0f 1e ...), the whitespace
 > separator in between can be chosen freely.

I've been looking at this for inclusion in gsl-1.4 and realised that
the fprintf function is not going to be portable between architectures
(64 vs 32 bit, big-endian vs little-endian).  I will just add the
binary frwite/fread functions.

Brian