'Return help page for tool identified by \'id\' if available'

@web.expose
def tool_help(self, trans, id):

    toolbox = self.get_toolbox()
    tool = toolbox.get_tool(id)
    (yield '<html><body>')
    if (not tool):
        (yield ("Unknown    tool    id    '%d'" % id))
    elif tool.help:
        (yield tool.help)
    else:
        (yield ("No    additional    help    available    for    tool    '%s'" % tool.name))
    (yield '</body></html>')
