Plans for better description of decays

[jiangyi15]

There are many ways can be implemeted to simplify the current description of decays.

• [x] Replace rules : support replace decay node with particles name when it is list. use

  decay:
  A: 
  - [ R, B]
  R: [ C, D]
  particle:
   R: [R1, R2]

  to produce

  decay:
  A: 
  - [ R1, B ]
  - [ R2, B ]
  R1: [ C, D ]
  R2: [ C, D ]

• [x] Properities from Resonaces.yml and override in config.yml. use

  # in Resonances.yml
  R1:
  J: 1
  P: +1
  mass: 1.0
  width: 0.05

  # in config.yml
  particle:
  R1:  
    mass:  1.1

  to produce

  # in config.yml
  particle:
  R1:
    J: 1
    P: +1
    mass: 1.1
    width: 0.05

• [ ] Support multiply particles of top nodes. (A -> B C D, B -> E F G)
  • aligned in each parts to avoid much combination.
  • combine the amplitude of them like a decay chain.
• [ ] Better way to deal with identical particles.