Refactors each TypeDispatcher to have its own separate collection
of types. Add isnan function which returns a boolean if that type
is present, otherwise returns the number 1 for true, and 0 for fase.
Also adds implicit conversion configuration option to Type constructor,
and institutes a numbers-only bundle, and supports argument matching
with implicit conversions.
Still need to test that a behavior that invokes implicit conversion ends up
with the conversion operation as a dependency (and so regenerates itself if
the conversion changes).
