Add last_error()

Signed-off-by: Norv <a.w.norv@gmail.com>

Conflicts:
	sources/database/Db-mysql.class.php
	sources/database/Db.class.php

Signed-off-by: Norv <a.w.norv@gmail.com>
several methods corrected and completed

Signed-off-by: Norv <a.w.norv@gmail.com>
Several functions, few updates along the rest of core files.

Signed-off-by: Norv <a.w.norv@gmail.com>
The rest of methods implemented

Signed-off-by: Norv <a.w.norv@gmail.com>
Replace and remove list_tables, table_sql and server_info (rarely used stuff)

Signed-off-by: Norv <a.w.norv@gmail.com>
Remove db_insert_sql (rarely used)

Signed-off-by: Norv <a.w.norv@gmail.com>
Remove backup stuff (rarely used), fix list_ables

Signed-off-by: Norv <a.w.norv@gmail.com>
Remove DbExtra files.

Signed-off-by: Norv <a.w.norv@gmail.com>