install.php: php 5.4 suggestion, remove imagick suggestion

imagick support is unsupported and deprecated

install.php

@@ -623,6 +623,13 @@ if ($step == 0) {
 		),
 		array(
 			'category' => 'PHP',
+			'name' => 'PHP ≥ 5.4',
+			'result' => PHP_VERSION_ID >= 50400,
+			'required' => false,
+			'message' => 'vichan works best on PHP 5.4 or better.',
+		),
+		array(
+			'category' => 'PHP',
 			'name' => 'mbstring extension installed',
 			'result' => extension_loaded('mbstring'),
 			'required' => true,
@@ -672,13 +679,6 @@ if ($step == 0) {
 		),
 		array(
 			'category' => 'Image processing',
-			'name' => 'Imagick extension installed',
-			'result' => extension_loaded('imagick'),
-			'required' => false,
-			'message' => '(Optional) The PHP <a href="http://www.php.net/manual/en/imagick.installation.php">Imagick</a> (ImageMagick) extension is not installed. You may not use Imagick for better (and faster) image processing.',
-		),
-		array(
-			'category' => 'Image processing',
 			'name' => '`convert` (command-line ImageMagick)',
 			'result' => $can_exec && shell_exec('which convert'),
 			'required' => false,