Properly dispose of text editors subscription

Fixes #156

Author: mnquintana

lib/main.coffee

@@ -14,11 +14,14 @@ module.exports =
       default: true
 
   activate: ->
-    atom.workspace.observeTextEditors (editor) ->
+    @editorsSubscription = atom.workspace.observeTextEditors (editor) ->
       editorElement = atom.views.getView(editor)
 
       BracketMatcherView ?= require './bracket-matcher-view'
       new BracketMatcherView(editor, editorElement)
 
       BracketMatcher ?= require './bracket-matcher'
       new BracketMatcher(editor, editorElement)
+
+  deactivate: ->
+    @editorsSubscription.dispose()