plscheme - plscheme: Initialize guile just once for every session.

Log Message:
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Initialize guile just once for every session. And define a global variable,
"shared", that's accessible by all procedures within the current session.
Furthermore, any definition issued by a procedure will be placed in the top
lexical scope at the initialization, which means related definition will be
accessible by other procedure calls within the same session too.

Modified Files:
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    plscheme:
        plscheme.c (r1.18 -> r1.19)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plscheme/plscheme/plscheme.c.diff?r1=1.18&r2=1.19)