Implement permission checks for adding and deleting line items in issue forms

lib/redmine_qbo_line_items.rb

@@ -12,10 +12,18 @@ module RedmineQboLineItems
 
   def self.setup
    unless Issue.ancestors.include?(LineItems::Patches::IssuePatch)
+      # Patches
       Issue.prepend LineItems::Patches::IssuePatch
+
+      # Hooks
       LineItems::Hooks::IssuesSaveHookListener
       LineItems::Hooks::QboHookListener
       LineItems::Hooks::ViewHookListener
+
+      # Administration menu extension
+      Redmine::MenuManager.map :admin_menu do |menu|
+        menu.push :redmine_qbo_lineitems, { controller: 'items', action: 'index' }, icon: 'list', caption: :label_items, html: { class: 'icon icon-list' }
+      end
     end
   end
 end