Work only on 4.02.1
Update TODO
Rename Makefile.ocamlmakefile -> Makefile.merlin
Travis: use only 4.02
Travis: remove minor compiler versions
PoC PPX
PPX: add support for caching cookies
Fix storage of ppx cookies
Emacs: rework error display infrastructure
New indexer runs inside merlin and doesn't require a db
PoC of interface reverse dependencies \o/

["users","of","module","Std"]
Indexer: index implementation
Add prefix expansion command
vim: "dwim" / prefix expansion on :Locate
vim: RFC, dwim on empty completion
Fix registration of global modules during expansion
Fix filtering of expansion results
vim: fix completion, add g:merlin_dwim_completion setting
Expansion: don't fallback to null path if there is no candidate