Some small code changes to adapt to requests for implementation of mixing.

Some small code changes to adapt to requests for implementation of mixing.
Some restyling and creation of header comments or function comments.

AliRsnDaughter:
- added a pointer to the owner event, used for event-related quantities
- changed where possible the dynamic_cast calls with static ones and ROOT RTTI
- added a new enum for particle types, in order to manage what is not present in AliPID
  (this should become the reference for the package, while AliPID compatibility is kept when applicable)
- added static functions to deal with this enumeration and recover mass and PDG codes
- moved the initialization of momentum vector to the "SetRef()" function, while "SetMass()" changes the mass only

AliRsnDaughterDef:
- propagated the static functions and native enum in AliRsnDaughter for mass assignment

AliRsnMother:
- added a pointer to the owner event used as reference (in case the two daughters point to different ones)
- propagated the new particle type enumeration in AliRsnDaughter
- reimplemented some getters as inline

AliRsnEvent:
- removed the static data members (make confusion with mixing event handler)
- moved here all methods for multiplicity computations (included the new one with SPD)
- renamed multiplicity computation methods ("GetMultiplicity()" disappeared and replaced by 4 methods)
- added a function to set an AliRsnDaughter object from absolute index
- added a line of code to set (*this) as owner event for a daughter set with "SetDaughter()"
- restyled some comments

AliRsnTarget:
- removed all static data members
- when target is not an event, a reference event is set to the owner of the daugher/mother
  and is used to compute event-related values when passing those objects to any computation

AliRsnCutESD2010:
- removed function with non-pointer arguments

AliRsnCutPID:
- added a security check to avoid NULL objects

AliRsnCutPIDTOF:
- propagate the event referencing using the daughter owner event

AliRsnFunction:
- removed a useless data member to distinguish between 1-daughter and 2-daughters functions
- some class restyling
- added a data-member for values computation, to avoid several new/deletes per job
- fixed a bug for variable binning in THnSparse outputs
- added a check to skip histogram filling when at least one of the computations for an object is failed

AliRsnMonitor:
- replaced the static daughter data member with a pointer (initialized to 0)
  --> this helps in fixing a coverity problem raised with a previous version

AliRsnValue:
- added some new values: (detector signals, new multiplicity, total momentum in TPC)
- moved the explicit computation of some values to the respective targets (event, mother, daughter)
- added some comments along the big "select" code

AliRsnVATProcessInfo:
- used events histogram returns to 2 bins
- "FillInfo()" method returns to require an AliRsnEvent argument (since static are removed)

AliRsnAnalysisManager:
- now the "ProcessAll" function to execute all computations requires teo AliRsnEvent arguments
  (again, because the static data members in AliRsnEvent have been removed)
- unified computations for 1-track and 2-track functions

all analysis tasks:
- propagate all modifications in function calls