class HHypListFiller: public HReconstructor

 Before init is called, all the tracks need to be added.
 Next the number of possible combinations is computed and a pid
 table with all permutaions is created. Next steps done are to init
 HypComb, HypList and PidTrackCand Containers

 cout<<" \n\n\n HHypListFiller::finalize() \n\n";

 Adds a particle type track to filler
      must be done before init is called

 Adds a missing particle to filler
      must be done before init is called

 just_a_test_for_debugging - the name says it
 -> creates pid_table
 -> copy to dummy hypcomb
 -> prints content

 computes number of combinations and number of pos/neg particle combination
 This function is normally called by init.

 Mathematics (Bronstein ;-)):
 Permutation of n elements in m groups with k1 to km elements each
 P=n! / ( k1! * k2! *...* km! )
 this is true for positive and negative independently
 -> everything is done for positive AND negativ particles

 the following things happen here:
 1) sort positive and negative particle IDs
   -> now every "difference" between two particles is one additional type
 2) now k1! * k2! ... is calculated
   -> if particle type changes, loop-last_index is k1, next is k2... last is km
 3) result is produkt of ks
 3) from these differences calculate number of combinations allcombination/doubles
 4) numberofcombinations is numberofpositive times numberofnegative

 Swap array-values for indizes a,b
 only used for permutations by FindNextPermutation
 and PermReverser

 Swap array-values from indizes a to b, meaning [a]<->[b] [a-1]<->[b-1] ...
 a MUST be smaller or equal than b or nothing will be done
 only used for permutations by FindNextPermutation

 Finds next permution of array. perms are deivered in right order
 starting from 11223 to 32211. If last one is reached, return false
 for the first call, array values MUST be in the right order!!!
 This is done by init() -> generateNumberOfCombinations
 Array values can be ANY number... negativ, 0, 1, 9999... dont care about this

 This function create all possible permutation for the given
 particles and stores it into pid_array, which is then copied
 to hypcomb for every event by fill_pid_table.
 number of possible combinations must be calculated before by
 generateNumberOfCombinations ...
 function is normally called by init

 introduced only for debugging