Update Travis to move to opam 1.2 and add OCaml 4.02.1.
Replace custom myocamlbuild code for -safe-string with a tag.

The tag is present in 4.02 release.
Replace optcomp with cppo.
Use a .gitignore appropriate for OASIS.
Update dependencies in .travis-ci.sh.
Regenerate OASIS.
Merge pull request #8 from whitequark/die-camlp4-die

replace optcomp by cppo, drop camlp4 dependency
Prepare version 0.8