Language Server Protocol (LSP) support for vim and neovim.

Features:
* Non-blocking asynchronous calls.
* Sensible completion
  Integrated well with deoplete or ncm2, or MUcomplete.
  Or simply with vim built-in `omnifunc`.
* Realtime diagnostics/compiler/lint message.
* Rename.
* Hover/Get identifier info.
* Goto definition.
* Goto reference locations.
* Workspace/Document symbols query
* Formatting
* Code Action/Quick Fix