Introduce digi container classes for each detector

Introduce digi container classes for each detector, replacing the simple concretization of DigiVector that we had up to now. The data representation remains the same, though, but the classes are now explicitly there and contain, when compiled against ROOT, a call to the ClassDef macro and thus a ROOT streamer. This should enable schema evolution in the future and thus backward compatibility in future changes to these classes.

algo/data/CMakeLists.txt

@@ -6,9 +6,9 @@ set(SRCS
   ${CMAKE_SOURCE_DIR}/core/data/CbmDefs.cxx
   ${CMAKE_SOURCE_DIR}/core/data/CbmAddress.cxx
 
-  ${CMAKE_SOURCE_DIR}/core/data/sts/CbmStsDigi.cxx
   ${CMAKE_SOURCE_DIR}/core/data/sts/CbmStsAddress.cxx
-
+  ${CMAKE_SOURCE_DIR}/core/data/sts/CbmStsDigi.cxx
+ 
   ${CMAKE_SOURCE_DIR}/core/data/rich/CbmRichDigi.cxx
 
   ${CMAKE_SOURCE_DIR}/core/data/much/CbmMuchDigi.cxx