Done with the docs for CowDb

http://agilewiki.wiki.sourceforge.net/CowDb

I've just finished reviewing the programming guides, updating the terminology and method calls. Should at least be somewhat helpful in getting started. Suggestions are welcome!

The biggest change of course was to the page on defining new persistent objects: http://agilewiki.wiki.sourceforge.net/DefiningNewPersistentObjects

I've also proposed a number of enhancements to CowDb, but I think those will wait for now: http://sourceforge.net/tracker/?group_id=106672&atid=645208

Right now, the most pressing item is the revival of COODBMS. It needs to be converted to the new CowDb API and serves as an advanced example of what can be done using CowDb.