revert the temporary fix for the missing hdr.tpl and add the ability to provide context sensitive help/documentation by passing the current URL path to the help module as $_REQUEST['cmd']. So we could create a special help page for settings/display or whatever. The only issue is whether this should be presented first with a link to the main help page, or if we put a line at the top of the main help page that says "I need help for settings/display". Also edited the help target window name, as "friendika-help" is a bit dated.
Merge https://github.com/friendica/red into zpull