Missing order_by() and other design questions? #59

Sorry for raising an issue - "discussions" are not enabled.

I have some questions:

1. Why is order_by() a mysql-only feature when it' s a standard sql clause used in all databases?
2. Why does limit expect a string instead of an integer?
3. No params support? I mean, we can compose the query conditionally, but what about the params so that we can prepare/run the query after? We' d have to reproduce the logic for adding a params array.

Thanks!