Add a new possibility in TTree::GetEntryNumberWithIndex.

// Return entry number corresponding to major and minor number
// Note that this function returns only the entry number, not the data
// To read the data corresponding to an entry number, use TTree::GetEntryWithIndex
// the BuildIndex function has created a table of Double_t* of sorted values
// corresponding to val = major + minor*1e-9;
// The function performs binary search in this sorted table.
// If it find an array value that maches val, it returns directly the
// index in the table.
// If an entry corresponding to major and minor is not found, the function
// returns a value = -lowest -1 where lowest is the entry number in the table
// immediatly lower than the requested value.


git-svn-id: http://root.cern.ch/svn/root/trunk@524 27541ba8-7e3a-0410-8455-c3a389f83636