Finalize ticket relations (closes issue 638)

- IssueUpdate.php: use dynamically set field validators for dynamically
  created fields; let relation_type0 and relation_issue0 exist at any time;
  check the validity of a user selection and combine the various input fields
  if possible; do the database updates for links; change the "change" format
  for labels to a more precise structure and no longer trust on a leading
  dash for removed labels
- IssueCreate.php: change the validator calls and field names
- Issue.php (getGroupedRelatedIssues): make it possible to return only a
  flat list of integers for easier processing
- 17AddIssueRelations.php: migrate the previous serialized "changes" format
  for issue comments to the new, more structured format (up and down)
- js-autocomplete.html: add support for multiple input fields
- view.html: output relation changes and wrap the related issues stanzas into
  paragraphs
- NEWS.mdtext: note the addition and the need for a specific version of Pluf

src/IDF/IssueComment.php

@@ -155,10 +155,18 @@ class IDF_IssueComment extends Pluf_Model
                     $out .= __('Owner:'); break;
                 case 'lb':
                     $out .= __('Labels:'); break;
+                case 'rel':
+                    $out .= __('Relations:'); break;
                 }
                 $out .= '</strong>&nbsp;';
-                if ($w == 'lb') {
-                    $out .= Pluf_esc(implode(', ', $v));
+                if ($w == 'lb' || $w == 'rel') {
+                    foreach ($v as $t => $ls) {
+                        foreach ($ls as $l) {
+                            if ($t == 'rem') $out .= '<s>';
+                            $out .= Pluf_esc($l);
+                            if ($t == 'rem') $out .= '</s> ';
+                        }
+                    }
                 } else {
                     $out .= Pluf_esc($v);
                 }