mysqlcompat - mysqlcompat: Update string and datetime functions to be

Log Message:
-----------
Update string and datetime functions to be valid on PostgreSQL 8.4 and higher. Drop cast, aggregate and operator if
existsbefore it is created. Retested on 8.4.x, 9.0.x, 9.1.x 

Modified Files:
--------------
    mysqlcompat:
        README (r1.11 -> r1.12)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/mysqlcompat/mysqlcompat/README?r1=1.11&r2=1.12)
        aggregate.sql (r1.2 -> r1.3)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/mysqlcompat/mysqlcompat/aggregate.sql?r1=1.2&r2=1.3)
        casts.sql (r1.2 -> r1.3)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/mysqlcompat/mysqlcompat/casts.sql?r1=1.2&r2=1.3)
        datetime.sql (r1.9 -> r1.10)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/mysqlcompat/mysqlcompat/datetime.sql?r1=1.9&r2=1.10)
        operators.sql (r1.2 -> r1.3)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/mysqlcompat/mysqlcompat/operators.sql?r1=1.2&r2=1.3)
        string.sql (r1.14 -> r1.15)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/mysqlcompat/mysqlcompat/string.sql?r1=1.14&r2=1.15)