Clarify licensing and bump minimum compiler to 4.02.3
- This library now depends on the
hashcons
package rather than
containing a fork of it. Now that there is no LGPL (+ linking exception)
code left, clarify that the license is ISC. Previously theopam
file claimed a mixture of licenses (#86 via @djs55). - Add multi-distro Travis testing support.
- Library now depends on OCaml 4.02+