Substantially support character encodings and "Highlight As" in changesets

Summary: Ref T5179. Ref T4045. Ref T832. We can now write non-utf8 hunks into the database, so try to do more reasonable things with them in the UI.

Test Plan: (See screenshots...)

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T832, T4045, T5179

Differential Revision: https://secure.phabricator.com/D9294

src/applications/diffusion/controller/DiffusionDiffController.php

@@ -68,6 +68,9 @@ final class DiffusionDiffController extends DiffusionController {
       array(
         'action' => 'rendering-ref')));
 
+    $parser->setCharacterEncoding($request->getStr('encoding'));
+    $parser->setHighlightAs($request->getStr('highlight'));
+
     $coverage = $drequest->loadCoverage();
     if ($coverage) {
       $parser->setCoverage($coverage);