Higher 0.3.1

Switch to the released version of topkg.

Higher 0.3.0

• Switch to topkg, and remove the ocamlfind dependency. See #7.

Higher 0.2.1

• Support for byte-code-only builds (#4). Thanks to @dbuenzli for the report (#3).

Higher 0.2: include example code

Added examples from:

      Lightweight Higher-Kinded Polymorphism
      Jeremy Yallop and Leo White
      Functional and Logic Programming 2014

Higher 0.1: initial release.

Merge pull request #19 from yallop/Obj.magic

Use unsafe casts instead of open GADTs for the implementation.