Add multiplex addon

Use case is codemirror breaks when using mutiple languages in one file

multiplexingMode is required by htmlembedded so needs multiplex addon.

Got this javascript error:

- "TypeError: undefined is not a function (near '...a.multiplexingMode...')"

This change fixes it.

See [1]

[1] https://github.com/codemirror/CodeMirror/blob/04d39f236a541104c3fccdfdf6ea164d6e4c74e7/mode/htmlembedded/htmlembedded.js#L18

Change-Id: I9c79d77c902dbb22271f33d9d6e2f9e50726d411

gr-editor/gr-editor.html

diff --git a/gr-editor/gr-editor.html b/gr-editor/gr-editor.html
index 6a2cfbb..7b7872f 100644
--- a/gr-editor/gr-editor.html
+++ b/gr-editor/gr-editor.html
@@ -23,30 +23,31 @@
 <script src="../bower_components/codemirror-minified/addon/edit/matchtags.js"></script>
 <script src="../bower_components/codemirror-minified/addon/edit/trailingspace.js"></script>
 <script src="../bower_components/codemirror-minified/addon/mode/simple.js"></script>
+<script src="../bower_components/codemirror-minified/addon/mode/multiplex.js"></script>
 <script src="../bower_components/codemirror-minified/mode/meta.js"></script>
-<script src="../bower_components/codemirror-minified/mode/clike/clike.js" ></script>
-<script src="../bower_components/codemirror-minified/mode/clojure/clojure.js" ></script>
-<script src="../bower_components/codemirror-minified/mode/css/css.js" ></script>
-<script src="../bower_components/codemirror-minified/mode/dart/dart.js" ></script>
-<script src="../bower_components/codemirror-minified/mode/dockerfile/dockerfile.js" ></script>
-<script src="../bower_components/codemirror-minified/mode/erlang/erlang.js" ></script>
-<script src="../bower_components/codemirror-minified/mode/go/go.js" ></script>
-<script src="../bower_components/codemirror-minified/mode/haskell/haskell.js" ></script>
-<script src="../bower_components/codemirror-minified/mode/htmlembedded/htmlembedded.js" ></script>
-<script src="../bower_components/codemirror-minified/mode/htmlmixed/htmlmixed.js" ></script>
-<script src="../bower_components/codemirror-minified/mode/javascript/javascript.js" ></script>
-<script src="../bower_components/codemirror-minified/mode/markdown/markdown.js" ></script>
-<script src="../bower_components/codemirror-minified/mode/php/php.js" ></script>
-<script src="../bower_components/codemirror-minified/mode/puppet/puppet.js" ></script>
-<script src="../bower_components/codemirror-minified/mode/python/python.js" ></script>
-<script src="../bower_components/codemirror-minified/mode/ruby/ruby.js" ></script>
-<script src="../bower_components/codemirror-minified/mode/sass/sass.js" ></script>
-<script src="../bower_components/codemirror-minified/mode/shell/shell.js" ></script>
-<script src="../bower_components/codemirror-minified/mode/soy/soy.js" ></script>
-<script src="../bower_components/codemirror-minified/mode/sql/sql.js" ></script>
-<script src="../bower_components/codemirror-minified/mode/velocity/velocity.js" ></script>
-<script src="../bower_components/codemirror-minified/mode/xml/xml.js" ></script>
-<script src="../bower_components/codemirror-minified/mode/yaml/yaml.js" ></script>
+<script src="../bower_components/codemirror-minified/mode/clike/clike.js"></script>
+<script src="../bower_components/codemirror-minified/mode/clojure/clojure.js"></script>
+<script src="../bower_components/codemirror-minified/mode/css/css.js"></script>
+<script src="../bower_components/codemirror-minified/mode/dart/dart.js"></script>
+<script src="../bower_components/codemirror-minified/mode/dockerfile/dockerfile.js"></script>
+<script src="../bower_components/codemirror-minified/mode/erlang/erlang.js"></script>
+<script src="../bower_components/codemirror-minified/mode/go/go.js"></script>
+<script src="../bower_components/codemirror-minified/mode/haskell/haskell.js"></script>
+<script src="../bower_components/codemirror-minified/mode/htmlembedded/htmlembedded.js"></script>
+<script src="../bower_components/codemirror-minified/mode/htmlmixed/htmlmixed.js"></script>
+<script src="../bower_components/codemirror-minified/mode/javascript/javascript.js"></script>
+<script src="../bower_components/codemirror-minified/mode/markdown/markdown.js"></script>
+<script src="../bower_components/codemirror-minified/mode/php/php.js"></script>
+<script src="../bower_components/codemirror-minified/mode/puppet/puppet.js"></script>
+<script src="../bower_components/codemirror-minified/mode/python/python.js"></script>
+<script src="../bower_components/codemirror-minified/mode/ruby/ruby.js"></script>
+<script src="../bower_components/codemirror-minified/mode/sass/sass.js"></script>
+<script src="../bower_components/codemirror-minified/mode/shell/shell.js"></script>
+<script src="../bower_components/codemirror-minified/mode/soy/soy.js"></script>
+<script src="../bower_components/codemirror-minified/mode/sql/sql.js"></script>
+<script src="../bower_components/codemirror-minified/mode/velocity/velocity.js"></script>
+<script src="../bower_components/codemirror-minified/mode/xml/xml.js"></script>
+<script src="../bower_components/codemirror-minified/mode/yaml/yaml.js"></script>
 
 <dom-module id="gr-editor">
   <template>