python - be: Add interfaces to secure_read and secure_write.

Log Message:
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Add interfaces to secure_read and secure_write.

These functions provide adventurous stored procedure authors with the ability to
read and write strings directly to and from the wire. The intent is to provide
the capacity to create custom subprotocols--such as that used by the remote
console, rc/slithe.

Additionally, refactor the linecache code to include the trailing newline with
each line in the list. pdb, sadly, appears to depend on each item having a
trailing newline. Also, prefix "procedure files" with a "/" so pdb doesn't get
"smart" and resolve the filename prior to handing it to the linecache.

Add client_host and client_port attributes to the Postgres module.

Modified Files:
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    be/src:
        module.c (r1.28 -> r1.29)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/module.c.diff?r1=1.28&r2=1.29)
        pl.c (r1.38 -> r1.39)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/pl.c.diff?r1=1.38&r2=1.39)