[development] auto_increment

[Nicolas Tostin]

> I just
> don't see anyone building support for new databases and especially not
> those that lack native sequences.
>

In fact there's an attempt to make one DB layer for Oracle, and Oracle
doesn't support auto_increment column, so there's a trick to achieve it with
triggers.
Btw, due to the chaotic use of sequences table (sometime it's used,
sometimes not), I think definitly it should be worked a little and RDMS
should support this auto increment feature.