Add _.remove, which removes an element from an array in place

src/atom/window.coffee

@@ -6,6 +6,7 @@ Keymap = require 'keymap'
 RootView = require 'root-view'
 
 require 'jquery-extensions'
+require 'underscore-extensions'
 
 # This a weirdo file. We don't create a Window class, we just add stuff to
 # the DOM window.

src/stdlib/underscore-extensions.coffee

@@ -0,0 +1,6 @@
+_ = require 'underscore'
+
+_.mixin
+  remove: (array, element) ->
+    array.splice(array.indexOf(element), 1)
+