\startStaff critical bug

[Bertalan Fodor]

Two bugs are documented here:

1. \startStaff fails to start ledger lines in some situations:
   - when there is a linebreak in the started staff
   - when stopped at the beginning of the staff

2. \stopStaff doesn't stop correctly when stopped at the beginning of 
the staff

\layout { }
\version "2.5.27"
\paper {
raggedright = ##t
}

\relative \new StaffGroup <<
\new Staff {
    c,8
  \stopStaff d e f g a b c |
  \startStaff
  d c b a g f e d | c d e f g a b c |
  c b a g f e d c 
}

 \new Staff {
  \stopStaff c d e f g a b c |
  \startStaff
  d c b a g f e d | c d e f g a b c |
  c b a g f e d c 
}

\context Staff = "3" { c'1  c1 c c }
>>