Pandoc 1.10 API changes
Update to directory 1.2

`directory-1.2` uses `time` rather than `old-time`, so the type signature of
`getModificationTime` has changed. As a result `TOD` and `getModificationTime`
return different types, and we get the following error.

    Yst/Build.hs:86:44:
        Couldn't match type `ClockTime'
                      with `time-1.4.0.1:Data.Time.Clock.UTC.UTCTime'
        Expected type: IO time-1.4.0.1:Data.Time.Clock.UTC.UTCTime
          Actual type: IO ClockTime
        In the expression: return $ TOD 0 0
        In the second argument of `catch', namely
          `(\ (_ :: SomeException) -> return $ TOD 0 0)'
        In a stmt of a 'do' block:
          destmod <- catch
                       (getModificationTime destpath)
                       (\ (_ :: SomeException) -> return $ TOD 0 0)

I am not sure about the canonical way to fix this. My fix is from trial and
error.
Linking submenu to nothing looks bad
Don't give an error msg
dont give error msg