Emit a grammar-changed event from edit session

This event is now listened for from the editor and
re-emitted under the editor namespace.  This removes
the need to monitor the syntax's grammars-loaded event
from both places and also mirrors the behavior of the
path-changed event.

src/app/edit-session.coffee

@@ -841,6 +841,7 @@ class EditSession
     if @languageMode.reloadGrammar()
       @unfoldAll()
       @displayBuffer.tokenizedBuffer.resetScreenLines()
+      @trigger 'grammar-changed'
       true
 
   getDebugSnapshot: ->

src/app/editor.coffee

@@ -395,8 +395,6 @@ class Editor extends View
         e.pageX = @renderedLines.offset().left
         onMouseDown(e)
 
-      @subscribe syntax, 'grammars-loaded', => @reloadGrammar()
-
     @scrollView.on 'scroll', =>
       if @scrollView.scrollLeft() == 0
         @gutter.removeClass('drop-shadow')
@@ -456,6 +454,9 @@ class Editor extends View
       @reloadGrammar()
       @trigger 'editor:path-changed'
 
+    @activeEditSession.on "grammar-changed.editor", =>
+      @trigger 'editor:grammar-changed'
+
     @trigger 'editor:path-changed'
     @resetDisplay()
 
@@ -1150,7 +1151,6 @@ class Editor extends View
     if grammarChanged
       @clearRenderedLines()
       @updateDisplay()
-      @trigger 'editor:grammar-changed'
     grammarChanged
 
   bindToKeyedEvent: (key, event, callback) ->