Support MySqlParameterCollection.AddWithValue

[caleblloyd]

Oracle's upcoming 7.x Connector/NET release adds a public AddWithValue method to MySqlParameterCollection

MySqlConnector's MySqlParameterCollection should add this method as well in order to maintain BC. Also, it seems like a convenient method to have.

[bgrainger]

This public API appears to be in 6.9 as well, so even more reason to add it.

[bgrainger]

Fixed in 0.16.0.