add EntityQuery to manage entity and query.
create Paginate filter.
to be used in model or entity manager.
rename FilterAbstract to RuleAbstract.
it is, after all, a base class for rules...
add Filters, a generic filter manager;
use Filters in ModelFilter for all models.
use event specific method for filter.
make Paginate filter cache-able.
add ForUpdate filter to setup select query for updates.
add a method to get ModelManager from em.
add a method to return Filter object.
add methods to add {filters|rules} to models.