Return diatonic integer scale degree from 1 to 7 corresponding to pitch transposed by integer number of staff_spaces.
abjad> pitch = Pitch(13)
abjad> pitch.degree
1
abjad> pitchtools.add_staff_spaces(pitch, 0)
1
abjad> pitchtools.add_staff_spaces(pitch, 1)
2
abjad> pitchtools.add_staff_spaces(pitch, 2)
3