Ambitus does not automatically detect range

Ubuntu 14.04, GIT commit: d0e6b72

1) new score
2) add notes, not all same pitch
3) drag ambitus symbol from Lines palette to initial clef

Result: it shows only the first note, not the highest or lowest.

This seems to be a side effect of recent change to add a "sameStaff" parameter to Segment::nextCR(). It fails in the case where no track parameter is passed in (and hence the default of -1 is used), because strack & etrack are not up correctly, I think.

There are likely other worse effects too, but the case with no track parameter isn't used all that often in the code.