Fixing typo in $this-db>->table() to $this->_db->table()
Fixing typo in method name DbUpdate::backupDb -> DbUpdate::_backupDb.
Fixing typo in query to check site table exists.
Allow silencing output for expected Db errors.
Merge branch 'dev' of github.com:nZEDb/nZEDb into dev

Conflicts:
	nzedb/build/nZEDb.xml
Manually updating versions.