Search engine: issue custom fields can now be searched.

Each issue custom field (excepting numeric, date and boolean fields) can be marked as "Searchable" (default to false).

git-svn-id: http://redmine.rubyforge.org/svn/trunk@994 e93f8b46-1217-0410-a6f0-8f06a7374b81

lang/de.yml

@@ -549,3 +549,4 @@ text_caracters_minimum: Muss mindestens %d Zeichen lang sein.
 setting_bcc_recipients: Blind carbon copy recipients (bcc)
 button_annotate: Annotate
 label_issues_by: Issues by %s
+field_searchable: Searchable