PostgreSQL binding

*Features*

 Written in Common Lisp, using ACL foreign function library.
 Also, uses defsystem and package named "pg".
 Minimal, simplistic sql function mimics ODBC syntax.

*Setting up and using PostgreSQL binding*

 Change the default directory in the system.cl file to the place you
 put it.

 Ensure that postgresql's postmaster process is running.
        (eg, ps aux | grep postmaster)
 If not, refer to PostgreSQL doc.

 Start Lisp in emacs

 Load the PostgreSQL shared library
 (load "libpq.so")  <--- note that is a "pq" not a "pg"

 For the first time, compile and load the system :pgsql
 Otherwise, just load it.

*Notes*

 The C code implies virtual packages of both pq and pg. I just
 chose one, "pg", based on what I thought sounded best.

 The support functions are extremely simplistic, partly on purpose.
 However, we could eventually take advantage of more advanced features
 in PostgreSQL, if the support functions  are further developed.