New decay models
Two new decay models are added, the first for phase-space with
minimal decay time requirement and the second for 3-body phase-space where
rectungular part of the Dalitz plot can be selected.
Test Plan: Test added to default set of tests to verify that models are doing what is expected.
Reviewers: jback, tlatham
Reviewed By: jback
Differential Revision: https://phab.hepforge.org/D28