Started on issue 544, extended commit details

* Scm.php: new SCM method "getChanges" which returns all available
  change information grouped by type
* Monotone.php: implement getChanges via get_revision
* <other scms>: rename "changes" member for getCommit to "diff" which
  matches better
* Source.php: query the commit's changes and set them in the template
* commit.html: render the changes, type-by-type. Link to the tree or
  the individual diff if applicable
* styles.css: some initial style sheet work

src/IDF/Scm/Mercurial.php

@@ -359,7 +359,7 @@ class IDF_Scm_Mercurial extends IDF_Scm
             }
         }
         $out = self::parseLog($log, 6);
-        $out[0]->changes = implode("\n", $change);
+        $out[0]->diff = implode("\n", $change);
         return $out[0];
     }