DB: started support for "magic" table classes.

***BREAKS BACKWARD COMPATIBILITY***
Db class methods _run, _insert, _update, _foundRows,
__buildInsUpdQuery, __buildParams and _buildLimit are now public
and their name no longer starts with underscores. (Es: run, insert,
etc...). Every call must be refactored.
Merge branch 'master' of https://github.com/gtozzi/dophp