Fix Scrutinizer issues in contacts/credits/crepair

- Add back uninitialized variables
- Fix formatting
- Use dba::selectFirst whenever possible

mod/credits.php

@@ -5,19 +5,17 @@
  * (only contributors to the git repositories for friendica core and the
  * addons repository will be listed though ATM)
  */
-
 use Friendica\App;
 
-function credits_content(App $a) {
+function credits_content()
+{
 	/* fill the page with credits */
-	$f = fopen('util/credits.txt', 'r');
-	$names = fread($f, filesize('util/credits.txt'));
-	$arr = explode("\n", htmlspecialchars($names));
-	fclose($f);
+	$credits_string = file_get_contents('util/credits.txt');
+	$names = explode("\n", htmlspecialchars($credits_string));
 	$tpl = get_markup_template('credits.tpl');
-	return replace_macros($tpl, array(
+	return replace_macros($tpl, [
 		'$title'  => t('Credits'),
 		'$thanks' => t('Friendica is a community project, that would not be possible without the help of many people. Here is a list of those who have contributed to the code or the translation of Friendica. Thank you all!'),
-		'$names'  => $arr,
-	));
+		'$names'  => $names,
+	]);
 }