class HMdcCellGroup: public TObject

_HADES_CLASS_DESCRIPTION

 HMdcCellGroup, HMdcCellGroup6, HMdcCellGroup12

 	This class and it's derived classes provide a mechanism to
 know with cells contributed to a particular hit or segment and
 how. They store therefore, a list of cells in different layers allowing
also to select one of the two possible signals in a given cell.

       HMdcCellGroup is never instantiated directly, but HMdcCellGroup6 or
HMdcCellGroup12 are used, where the number in the class name indicates
how many layers are available at maximum.

The info provided by this class is retrieved with the
following functions

 * Int_t getNCells(Int_t layer)
	Returns the number of cells in layer "layer" which contributed
	to the hit.

 * Int_t getCell(Int_t layer,Int_t idx)
      For idx=0 returns the cell number of the first fired cell
      For idx=1 returns the cell number of the second fired cell
	.... (maximum idx=3)

 * Int_t HMdcHit::getSignId(Int_t layer,Int_t idx)
	Returns signal id (time/distance) in cell designed by
	idx (same criterium as before).

 * Int_t setSignId(Int_t layer,Int_t cell, Int_t t1,t2=0,t3=0,t4=0)
	Sets the signal ids and base cell number for layer "layer"
	Input:
	  layer --> Number of layer to set
	  cell  --> Number of the first cell fired in this layer
	  t1 - t4 --> SignalId for cells: "cell"+0, "cell"+1 ... "cell"+4
	              Possible values are:
	                0 --> This cell has not fired
	                1 --> First signal (time/distance) was used
	                2 --> Second signal (time/distance) was used