Adds a __nonzero__ method so that checking truthiness does not cause __len__ to run
Adds protection around _xodb_schema for reopens
Adds query count ability to allow for nested queries.  As it was, running a nested query would automatically reopen (and therefore close in a replicated nvironment) the database of the calling query.
Merge pull request #7 from 7footmoustache/master

Adds a nonzero method to avoid running unnecessary len