Fix many encoding and architecture problems in Diffusion request and URI handling

Summary:
Diffusion request/uri handling is currently a big, hastily ported mess. In particular, it has:

  - Tons and tons of duplicated code.
  - Bugs with handling unusual branch and file names.
  - An excessively large (and yet insufficiently expressive) API on DiffusionRequest, including a nonsensical concrete base class.
  - Other tools were doing hacky things like passing ":" branch names.

This diff attempts to fix these issues.

  - Make the base class abstract (it was concrete ONLY for "/diffusion/").
  - Move all URI generation to DiffusionRequest. Make the core static. Add unit tests.
  - Delete the 300 copies of URI generation code throughout Diffusion.
  - Move all URI parsing to DiffusionRequest. Make the core static. Add unit tests.
  - Add an appropriate static initializer for other callers.
  - Convert all code calling `newFromAphrontRequestDictionary` outside of Diffusion to the new `newFromDictionary` API.
  - Refactor static initializers to be sensibly-sized.
  - Refactor derived DiffusionRequest classes to remove duplicated code.
  - Properly encode branch names (fixes branches with "/", see <https://github.com/facebook/phabricator/issues/100>).
  - Properly encode path names (fixes issues in D1742).
  - Properly escape delimiter characters ";" and "$" in path names so files like "$100" are not interpreted as "line 100".
  - Fix a couple warnings.
  - Fix a couple lint issues.
  - Fix a bug where we would not parse filenames with spaces in them correctly in the Git browse query.
  - Fix a bug where Git change queries would fail unnecessarily.
  - Provide or improve some documentation.

This thing is pretty gigantic but also kind of hard to split up. If it's unreasonably difficult to review, let me know and I can take a stab at it though.

This supplants D1742.

Test Plan:
  - Used home, repository, branch, browse, change, history, diff (ajax), lastmodified (ajax) views of Diffusion.
  - Used Owners typeaheads and search.
  - Used diffusion.getrecentcommitsbypath method.
  - Pushed a change to an absurdly-named file on an absurdly-named branch, everything worked properly.

{F9185}

Reviewers: nh, vrana, btrahan

Reviewed By: btrahan

CC: aran, epriestley

Differential Revision: https://secure.phabricator.com/D1921

src/applications/diffusion/controller/file/DiffusionBrowseFileController.php

@@ -403,22 +403,27 @@ final class DiffusionBrowseFileController extends DiffusionController {
         $targ = null;
       }
 
-      // Create the row display.
-      $uri_path = $drequest->getUriPath();
-      $uri_rev  = $drequest->getStableCommitName();
-      $uri_view = $view
-        ? '?view='.$view
-        : null;
+      $href = $drequest->generateURI(
+        array(
+          'action' => 'browse',
+          'stable' => true,
+        ));
+      $href = (string)$href;
 
-      $l = phutil_render_tag(
+      $query_params = null;
+      if ($view) {
+        $query_params = '?view='.$view;
+      }
+
+      $link = phutil_render_tag(
         'a',
         array(
-          'href' => $uri_path.';'.$uri_rev.'$'.$n.$uri_view,
+          'href' => $href.'$'.$n.$query_params,
         ),
         $n);
 
       $rows[] = $tr.$blame_info.
-        '<th class="diffusion-wide-link">'.$l.'</th>'.
+        '<th class="diffusion-wide-link">'.$link.'</th>'.
         '<td>'.$targ.$line.'</td></tr>';
       ++$n;
     }