Display multi-line commit message on commit diff page.

public/ng/css/gogs.css

@@ -1510,6 +1510,9 @@ The register and sign-in page style
 .commit-list .message span {
   max-width: 500px;
 }
+.commit-message {
+  white-space: pre-wrap;
+}
 .diff-head-box {
   margin-top: 10px;
 }

public/ng/less/gogs/repository.less

@@ -535,6 +535,11 @@
         }
     }
 }
+
+.commit-message {
+	white-space: pre-wrap;
+}
+
 .diff-head-box {
     margin-top: 10px;
     .panel-body {

templates/repo/diff.tmpl

@@ -17,7 +17,7 @@
         <div class="panel panel-info panel-radius diff-head-box">
             <div class="panel-header">
                 <a class="pull-right btn btn-blue btn-header btn-medium btn-radius" rel="nofollow" href="{{.SourcePath}}">{{.i18n.Tr "repo.diff.browse_source"}}</a>
-                <h4>{{.Commit.Message}}</h4>
+                <h4 class="commit-message">{{.Commit.Message}}</h4>
             </div>
             <div class="panel-body">
                 <span class="pull-right">