Add rulers addon

Allows for vertical rules to be shown.

Change-Id: I4a2cf1bfae15945e0f622045524c56b2cddc16a1

gr-editor/gr-editor.html

diff --git a/gr-editor/gr-editor.html b/gr-editor/gr-editor.html
index 7b7872f..fd8673e 100644
--- a/gr-editor/gr-editor.html
+++ b/gr-editor/gr-editor.html
@@ -17,6 +17,7 @@
 <link rel="import" href="gr-editor-styles.html">
 
 <script src="../bower_components/codemirror-minified/lib/codemirror.js"></script>
+<script src="../bower_components/codemirror-minified/addon/display/rulers.js"></script>
 <script src="../bower_components/codemirror-minified/addon/edit/closebrackets.js"></script>
 <script src="../bower_components/codemirror-minified/addon/edit/closetag.js"></script>
 <script src="../bower_components/codemirror-minified/addon/edit/matchbrackets.js"></script>
@@ -68,6 +69,9 @@
       .CodeMirror-linenumber {
         color: #757575;
       }
+      .CodeMirror-ruler {
+        border-left: 1px solid #ddd;
+      }
       .cm-tab:before {
         color: #757575;
         content: "\2192";

gr-editor/gr-editor.js

diff --git a/gr-editor/gr-editor.js b/gr-editor/gr-editor.js
index 029082d..bb9233e 100644
--- a/gr-editor/gr-editor.js
+++ b/gr-editor/gr-editor.js
@@ -66,7 +66,6 @@
         params.indentWithTabs = prefs.indent_with_tabs;
         // TODO(kaspern): Add support for keymaps.
         // params.keyMap = prefs.key_map_type.toLowerCase();
-        params.lineLength = prefs.line_length;
         params.lineNumbers = true;
         params.lineWrapping = prefs.line_wrapping;
         params.matchBrackets = prefs.match_brackets;
@@ -80,6 +79,7 @@
         // TODO(kaspern): Add support for themes.
         // params.theme = prefs.theme.toLowerCase();
 
+        params.rulers = [{column: prefs.line_length}];
         if (value && value.includes('\r\n')) {
           params.lineSeparator = '\r\n';
         }