Some tweaks to DB_DataObject

As meantioned earlier today, you can tell me I have gone too far and its a BC break, but if its useful then great :) http://www.electroteque.org/pear/DB_DataObject.diff I added some methods to handle transactions begin, commit , rollback and removed it from _query , but u can put that bak if u like heheh. I added a feature for a condition setter method so i could add custom whereAdd's, this happens during the _build_condition method. I also added a feature for setFrom to ignore empty values in a key, this was highly useful especailly for a search filter where I setup an advanced search form, but i dont want all fields to show up in the query only the ones i selected ! It was having unexpected results. I noticed some changes were made via cvs, how do i do an update on my end hehe.