Added support for (emulated) parametric queries.

Rev: lib/modules/Sql.pmod/msql.pike:1.6
Rev: lib/modules/Sql.pmod/mysql.pike:1.8
Rev: lib/modules/Sql.pmod/odbc.pike:1.4
Rev: lib/modules/Sql.pmod/postgres.pike:1.8
Rev: lib/modules/Sql.pmod/rsql.pike:1.2
Rev: lib/modules/Sql.pmod/sql_util.pmod:1.3
Rev: lib/modules/Sql.pmod/sybase.pike:1.2