locate: added basic command
Note: This is still WIP (consider it this commit as a pre-alpha release)
vim: first binding of locate command
locate: bugfix
locate: search for type declarations as well
makefile: tell ocamlbuild to generate cmt files.
protocol.md: updated with 'locate' command
locate: added "at pos" version
emacs: locate command.
emacs: Fixed stack of locate.
emacs: Fixed bug in `merlin-locate'.
locate: now works on record fields and constructors (incl. exceptions)
locate: better bindings in vim
locate: bugfixes
  - merlin failed on labels lookup
  - vim didn't send the good chunk of text to merlin
  - there was an index (out of bound) error in the vim plugin

bugfix: squash
locate: bugfix related to labels and constructors

It didn't work for types defined inside a module defined in the local file.
vim: locate command now syncs the buffer
vim: bound locate command on Locate
vim: added doc for 'Locate'
Merge branch 'locate-cmd' into experimental