Fixed typo in README: :opaque->::c/opaque. Also added a test for disequality of indexed sets with the same content but different indexes.
Added support for IFn, ILookup and the methods of Object.
Added a caveat with respect to ::c/opaque.
Release 0.2.0.

disj no longer leaks memory!

At least, none that's our fault.

Unfortunately, core.logic.pldb keeps some key->#{} key/value pairs around.