MetronomeMark does not obey staff-padding

[Bryan Stanbridge]

Greetings,

I'm not sure if this is a bug, but given my tests, I suspect it is (so I 
 copied the bug list). It appears that the MetronomeMark object does 
not pay attention to staff-padding. Does it not have any reference 
points defined for staff-padding perhaps? Here's my simple test version.

\version "2.10.20"

\score {
  \new Staff {
    \tempo 4=120
    c'4
    \override Score.MetronomeMark #'staff-padding = #5
    \tempo 4=100
    c'4
    \override Score.MetronomeMark #'extra-offset = #'(0 . 5)
    \tempo 4=80
    c'4
  }
}

I included the extra-offset just to verify I had the correct grob 
construction, and that works, so I do. If you want to remove that part 
from the bug report, please feel free.

If anyone has a work-around, it'd be appreciated (my tempo indications 
are colliding with my vocal dynamics throughout an entire lieder cycle).

Cheers,

Bryan...