Add Elixir support.

README.md

@@ -228,6 +228,9 @@ Here is a list of formatprograms that are supported by default, and thus will be
 * `fprettify` for modern __Fortran__.
   Download from [official repository](https://github.com/pseewald/fprettify). Install with `./setup.py install` or `./setup.py install --user`.
 
+* `mix format` for __Elixir__.
+  `mix format` is included with Elixir 1.6+.
+
 ## Help, the formatter doesn't work as expected!
 
 If you're struggling with getting a formatter to work, it may help to set vim-autoformat in

plugin/defaults.vim

@@ -439,3 +439,12 @@ endif
 if !exists('g:formatters_fortran')
     let g:formatters_fortran = ['fprettify']
 endif
+
+" Elixir
+if !exists('g:formatdef_mix_format')
+    let g:formatdef_mix_format = '"mix format -"'
+endif
+
+if !exists('g:formatters_elixir')
+    let g:formatters_elixir = ['mix_format']
+endif