[Dcmlib] New Feature : Extention of SerieHelper

[Jean-Pierre Roux]

To help archive search, this mail, redundant with my previous commit :

SerieHelper Extention : stage 1
---------------------
 In the following stuff,  'XCoherent' stands for 'Extra Coherent',
  (The name 'Coherent' would be enough but it was used before;
  I don't want to put a bomb in the code)
  Any 'better name' is welcome !

 Add some methods, to split a 'SingleSerieUID' Fileset into 'Extra 
Coherent'  FileSets.
   They return a std::map of 'Filesets' (actually : std::vector of 
gdcm::File*)
   The key is the 'Orientation', the 'Position' or the 'Tag value' .
 
  -  XCoherentFileSetmap SplitOnOrientation(FileList *fileSet);
 -   XCoherentFileSetmap SplitOnPosition(FileList *fileSet);
  -  XCoherentFileSetmap SplitOnTagValue(FileList *fileSet,
                                            uint16_t group, uint16_t 
element);
                       
 Theese methods must be called by user, depending on what he wants to do, at
 application time.
 - *he* only  knows what his Series contain !-

(We shall think later about the user friendly accesors we should add, 
and their names)

JPRx