Ternary to null coalescing

Use null coalescing operator ?? where possible.

Closes GH-528.

eol.php

@@ -61,7 +61,7 @@
 							</a>
 						</td>
 						<td>
-							<?php echo isset($BRANCH_NOTES[$branch]) ? $BRANCH_NOTES[$branch] : ''; ?>
+							<?php echo $BRANCH_NOTES[$branch] ?? ''; ?>
 					</td>
 				</tr>
 			<?php endforeach ?>

manual/add-note.php

@@ -88,9 +88,8 @@
     // No error was found, and the submit action is required
     if (!$error && strtolower($_POST['action']) != "preview") {
 
-        $redirip = isset($_SERVER['HTTP_X_FORWARDED_FOR']) ?
-                   $_SERVER['HTTP_X_FORWARDED_FOR'] :
-                   (isset($_SERVER['HTTP_VIA']) ? $_SERVER['HTTP_VIA'] : '');
+        $redirip = $_SERVER['HTTP_X_FORWARDED_FOR'] ??
+                   ($_SERVER['HTTP_VIA'] ?? '');
 
         // Post the variables to the central user note script
         $result = posttohost(

manual/vote-note.php

@@ -9,8 +9,8 @@
 $error = false;
 $thankyou = false;
 $headerset = false;
-$BACKpage = htmlspecialchars(isset($_REQUEST['page']) ? $_REQUEST['page'] : '');
-$BACKid = htmlspecialchars(isset($_REQUEST['id']) ? $_REQUEST['id'] : '');
+$BACKpage = htmlspecialchars($_REQUEST['page'] ?? '');
+$BACKid = htmlspecialchars($_REQUEST['id'] ?? '');
 $link = "/{$BACKpage}#{$BACKid}";
 $master_url = "https://main.php.net/entry/user-notes-vote.php";