check string with hammer&pulls

[BB]

feature request check string with hammer&pulls

If one transfers music to tabs beside the problem of ommited notes in case
of not defined strings another problem arises with hammer ons and pull offs
with different strings.

Example code:
\version "2.16.2"


    \new TabStaff {
    \key g \major
    \tabFullNotation
    \stemDown
     {
      \times 2/3{d^" P " (c)^" H" (d)} 
      d^" P" (c\5)
      \times 2/3{gis,^" H " (f)^" P" (g)} 
      {g,8^"H" (a)} <d b g>8 [g,] 
  }
    }

Lilypond simply could check if the note just befor a hammer or pull  and the
note after a hammer or pull are on the same string. If not -> a qualified
error message (with line number and position). 


Regards