Demographics1D: Add three-epoch model
Demographics1D: Add three-epoch model



git-svn-id: 4c7b13231a96299fde701bb5dec4bd2aaf383fc6@250 979d6bd5-6d4d-0410-bece-f567c23bd345

paulirish/dadi,paulirish/dadi,RyanGutenkunst/dadi,ChenHsiang/dadi,yangjl/dadi,cheese1213/dadi,cheese1213/dadi,niuhuifei/dadi,yangjl/dadi,RyanGutenkunst/dadi,ChenHsiang/dadi,beni55/dadi,niuhuifei/dadi,beni55/dadi