class HKalInput: public TObject

 It is recommended to use the constructor
 HKalInput(Int_t refID, HKalDetCradle *detCradle)
 instead where the object will be initialized correctly.
 This empty constructor sets all pointers to NULL. To use the object
 the following still has to be done afterwards:
 Do spectrometer setup + Hades creation ....
 To set the pointer to detector cradle:
 setDetectorCradle(detCradle)  // set pointer to detector cradle
 To get pointer to categories, HMdcSizesCells, magnet and B-field
 parameters:
 init(refID)                   // gets categories

 Assumes spectrometer setup + Hades creation have been performed ....
 This constructor sets all needed class members.
 refID:     runtime ID
 detCradle: pointer to Hades detector cradle

 calculates 2 coordinate points from segment.

 Clear the categories (for macros in MakeCode style).

 Retries the pointer to needed input categories. Creates
 iterators.

 Initialize HMdcTrackGFieldPar and HMagnetPar for run refID.
 If the container already exists it will not
 be created a second time.

 Initialize HMdcSizesCells for run refID.
 If the container already exists it will not
 be created a second time.

 Fills 4 hits in sector coordinates system to allhits array.
 Loops over HMdcTrkCand Category for the next for hits. The
 iterator for the category has to be reset by hand at the begin
 of each event. Return 0 if no next candidate has been found.
 The errors of the hits will be taken from HMdcSeg and can be scaled
 by scaleErr.

 allhits: array with HKalMdcHit objects (return value. Existing content of array will be deleted.)
 measDim: dimension of measurement vector
 scaleErr: scale errX and errY by this factor

 Fills drift chamber wire hits with the drift time as measurement vector
 to allhits array.
 Loops over HMdcTrkCandIdeal Category for the next four hits. The
 iterator for the category has to be reset by hand at the begin
 of each event. Return 0 if no next candidate has been found.

 output:
 allhits: array with HKalMdcHit objects (Existing content of array will be deleted!)
 input:
 minLayInSeg:   minimum number of layers in the inner segment needed to fill allhits
 minLayOutSeg:  minimum number of layers in the outer segment needed

 Fills drift chamber wire hits with the drift time as measurement vector
 to allhits array.
 If there are two competing hits in an MDC layer, only the one with the
 smaller drift time will be used.
 Loops over HMdcTrkCandIdeal Category for the next four hits. The
 iterator for the category has to be reset by hand at the begin
 of each event. Return 0 if no next candidate has been found.

 output:
 allhits: array with HKalMdcHit objects (Existing content of array will be deleted!)
 input:
 minLayInSeg:   minimum number of layers in the inner segment needed to fill allhits
 minLayOutSeg:  minimum number of layers in the outer segment needed

 Return TObjArray with pointer to HGeantMdc objects for the track.
 if midplane == kTRUE  fill only points for layer == 6.
 if midplane == KFALSE fill only points for layer < 6.

 Return pos and dir from HGeantMdc.
 if sectorCoord == kTRUE the points will be transformed
 to sector coordinate system.