Restore backwards compatibility

When status indicators were added, backwards compatibility was unnecessarily
broken. This makes things like looking at old non-rebased branches, or running
git bisect, unnecessarily annoying. This change adds an is_callable to restore
backwards compatibility and removes the version check that was added in response
to this break.

Change-Id: Ia05aa73a1b027e667c52f54b6d6fdf6f42bbbadf

Vector.php

@@ -22,12 +22,6 @@
  * @ingroup Skins
  */
 
-if ( version_compare( $GLOBALS['wgVersion'], '1.25c', '<' ) ) {
-	echo 'This version of the Vector skin requires at least MediaWiki 1.25, you have ' . $GLOBALS['wgVersion'] .
-		'. You can download a more appropriate version here: https://www.mediawiki.org/wiki/Special:SkinDistributor/Vector';
-	exit();
-}
-
 $GLOBALS['wgExtensionCredits']['skin'][] = array(
 	'path' => __FILE__,
 	'name' => 'Vector',

VectorTemplate.php

@@ -102,7 +102,11 @@ class VectorTemplate extends BaseTemplate {
 			<?php
 			}
 			?>
-			<?php echo $this->getIndicators(); ?>
+			<?php
+			if ( is_callable( array( $this, 'getIndicators' ) ) ) {
+				echo $this->getIndicators();
+			}
+			?>
 			<h1 id="firstHeading" class="firstHeading" lang="<?php
 			$this->data['pageLanguage'] =
 				$this->getSkin()->getTitle()->getPageViewLanguage()->getHtmlCode();