Log Message:
-----------
Support Snapshot Isolation level correctly.
Modified Files:
--------------
Npgsql2/src/Npgsql:
NpgsqlTransaction.cs (r1.8 -> r1.9)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/npgsql/Npgsql2/src/Npgsql/NpgsqlTransaction.cs?r1=1.8&r2=1.9)