add overloaded methods for various types to the Query class

Currently, all types other than strings must go through the ComplexKey class. This may not be the best approach since it leads to a bit of oddness with needing to tell the ComplexKey class to handle a single element differently.

One alternative is to improve the Query class to handle other types, then deprecate the special handling in the ComplexKey class and change the behavior for a single element. This would be a small API change, but maybe small enough that with sufficient warning, we can do it in a minor release.