Hide QR-Code button if PHP-GD is not installed

Keep it as an optional dependency.

program/steps/addressbook/show.inc

@@ -42,7 +42,10 @@ if ($cid && ($record = ($CONTACT_RECORD ?: $CONTACTS->get_record($cid, true))))
 // get address book name (for display)
 rcmail_set_sourcename($CONTACTS);
 
+// Disable qr-code if php-gd is not installed
+$OUTPUT->set_env('qrcode', function_exists('imagecreate'));
 $OUTPUT->add_label('qrcode');
+
 $OUTPUT->add_handlers(array(
     'contacthead'    => 'rcmail_contact_head',
     'contactdetails' => 'rcmail_contact_details',

skins/classic/templates/contact.html

@@ -21,7 +21,9 @@
   </div>
   <p>
     <roundcube:button command="edit" type="input" class="button" label="editcontact" condition="!ENV:readonly" />
+    <roundcube:if condition="env:qrcode" />
     <roundcube:button command="qrcode" type="input" class="button" label="qrcode" />
+    <roundcube:endif />
   </p>
 </div>
 <script type="text/javascript">rcube_init_tabs('contacttabs')</script>

skins/larry/templates/contact.html

@@ -25,7 +25,9 @@
 
 <div id="headerbuttons" class="formbuttons">
 	<roundcube:button command="edit" type="input" class="button mainaction" label="editcontact" condition="!ENV:readonly" />
+	<roundcube:if condition="env:qrcode" />
 	<roundcube:button command="qrcode" type="input" class="button" label="qrcode" />
+	<roundcube:endif />
 </div>
 
 <roundcube:include file="/includes/footer.html" />