prefix - prefix: Implement prefix_range send and recv functions

Log Message:
-----------
Implement prefix_range send and recv functions

Modified Files:
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prefix:
prefix.c (r1.38 -> r1.39)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/prefix/prefix/prefix.c.diff?r1=1.38&r2=1.39)
prefix.sql.in (r1.17 -> r1.18)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/prefix/prefix/prefix.sql.in.diff?r1=1.17&r2=1.18)