Display links to editor in Differential and Diffusion

Summary:
It is possible to open a file in editor by registering a custom URI scheme
(pseudo-protocol). Some editors register it by default.
Having links to open the file in external editor is productivity booster
although it is a little bit harder to set up.
There are several other tools using file_link_format configuration directive
(XDebug, Symfony) to bind to this protocol.
I've added the example with editor: protocol which can be used as a proxy to
actual editor (used by Nette Framework:
http://wiki.nette.org/en/howto-editor-link).

Test Plan:
Configure Editor Link in User Preferences.
Register URI scheme in OS.
Open a file in Diffusion. Click on the Edit button.
Open a revision in Differential. Click on the Edit button.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, epriestley

Differential Revision: https://secure.phabricator.com/D1422

src/applications/differential/view/changesetlistview/DifferentialChangesetListView.php

@@ -25,6 +25,7 @@ class DifferentialChangesetListView extends AphrontView {
   private $renderURI = '/differential/changeset/';
   private $whitespace;
   private $standaloneViews;
+  private $user;
   private $symbolIndexes = array();
   private $repository;
   private $diff;
@@ -44,6 +45,11 @@ class DifferentialChangesetListView extends AphrontView {
     return $this;
   }
 
+  public function setUser(PhabricatorUser $user) {
+    $this->user = $user;
+    return $this;
+  }
+
   public function setRevision(DifferentialRevision $revision) {
     $this->revision = $revision;
     return $this;
@@ -133,6 +139,19 @@ class DifferentialChangesetListView extends AphrontView {
           $meta['rightURI'] = (string)$detail_uri->alter('view', 'new');
         }
 
+        if ($this->user) {
+          $path = ltrim(
+            $changeset->getAbsoluteRepositoryPath($this->diff, $repository),
+            '/');
+          $line = 1; // TODO: get first changed line
+          $editor_link = $this->user->loadEditorLink($path, $line, $repository);
+          if ($editor_link) {
+            $meta['editor'] = $editor_link;
+          } else {
+            $meta['editorConfigure'] = '/settings/page/preferences/';
+          }
+        }
+
         $detail_button = javelin_render_tag(
           'a',
           array(
@@ -145,7 +164,6 @@ class DifferentialChangesetListView extends AphrontView {
           "View Options \xE2\x96\xBC");
       }
 
-
       $detail->setChangeset($changeset);
       $detail->addButton($detail_button);
       $detail->setSymbolIndex(idx($this->symbolIndexes, $key));