A slightly modified patch from Rong Nguyen for "Render multiMenu problem when linktype="hidden-form"" https://issues.apache.org/jira/browse/OFBIZ-5557

Scenario:
1. Go to Content webapp
2. Go to CompDoc menuitem
3. Search
4. Go to 'Tree' view
5. We can not use 'Up' and 'Down' function

When menu with linktype="hidden-form" was render for each menu, they has the same name for form element, so it cause error.
My solution is add extra attribute(extra-index) for Menu, and then in menu definition we provide this attribute and the forms with different name will be rendered.
My implement was tested in this bug for Content webapp

jleroux: I have simply amended the up and down labels to have them more legible. I'd have preferred to not have all uppercased, but ran out of time for such a trivial change


git-svn-id: https://svn.apache.org/repos/asf/ofbiz/trunk@1576891 13f79535-47bb-0310-9956-ffa450edef68