Use SQL::Maker::SQLType to pass around the typed parameters

As discussed in #132, strict mode of SQL::Maker disallows the use of arrayrefs as bind parameters, and thus Teng needs to use `SQL::Maker::SQLType` for passing the typed parameters around.

Note:  Programming interface provided by `SQL::Maker::SQLType` is awkward (in the sense that a) designates scalarrefs to be used for passing in the value, b) does not provide a way to fetch the value-type pair in a style that is easy to be passed to `$sth->bind_param`).  However after discussing with @tokuhirom, the conclusion is to not change the current API.