Draft: Add DecFiles for D0 -> KSpipi decays from B mesons secondary vertices
Create DecFiles for the ParticleGun production of D^0\rightarrow K_S^0\pi^+\pi^-
decays from B
mesons secondary vertices.
The D^0
decays through the D_Dalitz resonant model.
These DecFiles are based on similar DecFiles for the D^0\rightarrow K^+K^-
decays from B
mesons secondary vertices: EventType 11874014 and EventType 12873401.