MDL-61056 feedback: Fix the response navigation links

Floats are evil and unreliable. Even with the clearfix class added to
the response_navigation wrapper, the Next link would remain unaligned.
We need a proper three columns layout here.

It did not feel necessary to introduce a special template here so I'm
making use of the core one.

mod/feedback/show_entries.php

@@ -119,10 +119,24 @@
             $anonresponsestable->get_reponse_navigation_links($completedrecord);
 
     echo html_writer::start_div('response_navigation');
-    echo $prevresponseurl ? html_writer::link($prevresponseurl, get_string('prev'), ['class' => 'prev_response']) : '';
-    echo html_writer::link($returnurl, get_string('back'), ['class' => 'back_to_list']);
-    echo $nextresponseurl ? html_writer::link($nextresponseurl, get_string('next'), ['class' => 'next_response']) : '';
+
+    $responsenavigation = [
+        'col1content' => '',
+        'col2content' => html_writer::link($returnurl, get_string('back'), ['class' => 'back_to_list']),
+        'col3content' => '',
+    ];
+
+    if ($prevresponseurl) {
+        $responsenavigation['col1content'] = html_writer::link($prevresponseurl, get_string('prev'), ['class' => 'prev_response']);
+    }
+
+    if ($nextresponseurl) {
+        $responsenavigation['col3content'] = html_writer::link($nextresponseurl, get_string('next'), ['class' => 'next_response']);
+    }
+
+    echo $OUTPUT->render_from_template('core/columns-1to1to1', $responsenavigation);
     echo html_writer::end_div();
+
 } else {
     // Print the list of responses.
     $courseselectform->display();

mod/feedback/styles.css

@@ -86,14 +86,11 @@
 }
 
 .path-mod-feedback .response_navigation a {
-    display: inline-block;
+    display: block;
 }
 
 .path-mod-feedback .response_navigation a.back_to_list {
-    margin: auto;
-    float: right;
-    left: -50%;
-    position: relative;
+    text-align: center;
 }
 
 .path-mod-feedback .response_navigation .prev_response:before {
@@ -113,9 +110,9 @@
 }
 
 .path-mod-feedback .response_navigation .next_response {
-    float: right;
+    text-align: right;
 }
 
 .path-mod-feedback .response_navigation .prev_response {
-    float: left;
+    text-align: left;
 }

mod/feedback/version.php

@@ -24,7 +24,7 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$plugin->version   = 2017111300;       // The current module version (Date: YYYYMMDDXX)
+$plugin->version   = 2017111301;       // The current module version (Date: YYYYMMDDXX)
 $plugin->requires  = 2017110800;    // Requires this Moodle version
 $plugin->component = 'mod_feedback';   // Full name of the plugin (used for diagnostics)
 $plugin->cron      = 0;