add initilialization for parent member of TrueParticle

[mt82]

Added a initialization value to the parent member of TrueParticle

[PetrilloAtWork]

You know what? This type of mistakes is being hunting us since forever, and I am electing you as the victim who's going to pay for it.

Please change the header code removing the constructors and placing all the initialisation in the line the data member is declared.
For example:

struct WireInfo {
    uint16_t wire = uint16_t(-1); //!< Wire number
    uint16_t plane = uint16_t(-1); //!< Plane number
    uint16_t tpc = uint16_t(-1); //!< TPC number
    uint16_t channel = uint16_t(-1); //!< Channel number
    int16_t tdc0 = -1; //!< TDC tick of the first ADC value
    std::vector<short> adcs; //!< List of ADC values
  };

And guess what? in doing this example I already caught two mistakes (the construction value for tdc0 was cast to uint16_t even if the variable is signed, int16_t; and channel was not initialised).
This is not new rule: [CF-155]. The idea is that when a person adds a variable in the list they're more likely to notice that all other are being initialised, and do the same for the new one.

If you don't feel like doing that, let me know and I'll add the commit to this branch.