[Patch] Add support for DB->quoteEntity and Make $__DB = more consistent

This patch adds support to DB_DataObject to quote table and column names with the DB function quoteEntity(). Note: I just submitted the quoteEntity patch, so to use this, you must have installed the DB patch. If the DB patch is altered before submission to CVS, I will alter this patch accordingly. This feature is by default off, but can be turned on by setting: quote_entities = 1 in the DataObject.ini. All functions which take SQL code directly will not be quoted. They must be quoted by the user (using DB::quoteEntity() of course). This will have to be mentioned in the docs. I'm not sure about some of the functions. selectAdd() is normally used with columns, but may be, say, a function call, so I removed my quiting code from there. However, selectAs() looks like it is made for columns, so I left my code in. Is this correct? NONE of my code takes into account that the table/column could be pre-quoted. Technically, this should probably go in the DB function (although I didn't add it there, either). While working on this patch, I also noticed that many functions were getting $_DB_DATAOBJECT['CONNECTIONS'][$this->_database_dsn_md5] directly instead of using getDatabaseConnection, so I changed all that I could find. I also found two possible bugs while working on this pertaining to joinAdd. Bugs 404 and 405. I have tested my changes with a small test script. If you would like me to send that, just ask. -- paperCrane <Justin Patrin>