python - lo: Convenience interface to pg_config executables.

Log Message:
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Convenience interface to pg_config executables.

import postgresql.utility.config as cf
i = cf.instance()
i.version, i.pkglibdir, i.includedir, i.includedir_server, etc.

Added Files:
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lo/postgresql/utility:
config.py (r1.1)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/lo/postgresql/utility/config.py?rev=1.1&content-type=text/x-cvsweb-markup)