Better Error Message Handling

In OpenERP now we have a better Warning message system thanks to
`warning` module, so now we can have the customised message depending
on the user / language.

Still OpenERP lacking of the error message handling,
specially which given from database (PostgreSQL, MySQL)

like mysql (https://code.launchpad.net/~openerp-commiter/openobject-server/server-sa)

So therefor, we need a common system where we can have common error message depending on
databases codes, where each Database packages supplied codes for the different type of
errors.

PostgreSQL : http://www.postgresql.org/docs/8.1/static/errcodes-appendix.html
MySQL : http://dev.mysql.com/doc/refman/5.1/en/error-messages-server.html

this will be implemented in the base system and not as a module, but of course,
using OpenERP API only.

Any Suggations ??