Update META to use ppx support in ocamlfind >=1.5.
Add .gitignore.
Add opam file and reflect ocamlfind >=1.5 dependency.
Rename sedlex_ppx.ml to ppx_sedlex.ml for consistency.
Make ppx_sedlex.ml use ppx_metaquot.
Merge branch 'master' of https://github.com/whitequark/sedlex