Render the Code view on the server (minus syntax highlighting) (#2942)

* render code view server side

* remove debug print

* fix multiline selection bug

* change string concatenation to bytes.Buffer for efficiency

* Fix newlines added by previous for hljs

* fix selection highlighting

* make css changes in .less

templates/repo/view_file.tmpl

@@ -44,7 +44,7 @@
 						{{if .IsFileTooLarge}}
 							<td><strong>{{.i18n.Tr "repo.file_too_large"}}</strong></td>
 						{{else}}
-							<td class="lines-num"></td>
+							<td class="lines-num">{{.LineNums}}</td>
 							<td class="lines-code"><pre><code class="{{.HighlightClass}}"><ol class="linenums">{{.FileContent}}</ol></code></pre></td>
 						{{end}}
 						</tr>