libpqtypes - libpqtypes: Added support for PQspecPrepare.

Log Message:
-----------
Added support for PQspecPrepare.  This required centralizing spec format parsing code into spec.c, so several functions
likeputf and getf can make use of it.  Added a man page for the new function, a regression test and updated the change
log.

Added Files:
-----------
    libpqtypes/src:
        spec.c (r1.1)

(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/libpqtypes/libpqtypes/src/spec.c?rev=1.1&content-type=text/x-cvsweb-markup)