Random sampling extension for GSL

[Joseph Wakeling <joseph dot wakeling at webdrake dot net>]

As discussed in earlier emails, I've created a project page at GitHub
for the new random sampling extension:
http://github.com/WebDrake/GrSL

The design is intended to facilitate painless (to users) incorporation
into GSL if/when that becomes desirable, while working well at present
as a standalone library.

It currently implements Algorithm A from Vitter (1984) and has a small
daft demo program included.  It builds OK on my Ubuntu Linux system
using the GNU Autotools, but I make no promises at present. :-)

I will probably migrate to Savannah as/when functionality and interest
grow sufficient -- for now it didn't seem worth bothering their
reviewers with a barely-started project.

I'll post a small announcement on the help-gsl list as well once it's a
little more developed.

Review, feedback and contributions all welcome. :-)

Thanks & best wishes,

    -- Joe