Add basic LSP support

Still needs to be documented, but includes support for the following
languages:

+ C/C++/ObjC
+ Go
+ Java
+ Javascript
+ OCaml
+ PHP
+ Python
+ Ruby
+ Scala
+ Swift
+ HTML/CSS

Relevant to #460, #716, #1186

init.example.el

@@ -67,6 +67,7 @@
        ;;editorconfig      ; let someone else argue about tabs vs spaces
        ;;ein               ; tame Jupyter notebooks with emacs
        ;;gist              ; interacting with github gists
+       ;;lsp
        ;;macos             ; MacOS-specific commands
        ;;magit             ; a git porcelain for Emacs
        ;;make              ; run make tasks from Emacs