Update for new ppx_tools.
ocamlfind is only a build dependency.
Improve build/release systems.
Fix local builds.
Rename ~name and ~prefix of Ppx_deriving.attr and Ppx_deriving.Arg.payload to ~deriver.
Depend on ocamlfind 1.5.4.
Improve option parser.
Factor out attribute parsing methods in standard derivers.
Add dummy option parsers that raise on any option.
Buildsystem improvements.
Add a note on buildsystem integration.
Show, Eq, Ord: handle `_`.
Fix whitespace violations.
Set default loc to typ.ptyp_loc in [%derive...] (fixes #13).
add an example of deep tree, to show how it prints, in src_examples/print_test
slightly different printing of variants
fix tests
Merge pull request #15 from c-cube/update_show

slightly different printing of variants
Add version to opam file (fixes #10).
Don't invoke opam query for targets other than release.