outline/userInput.js
function clipboardInit () {
      outline.clipboard = {}
      outline.clipboard.objects = []
      outline.clipboard.predicates = []
      outline.clipboard.all = []
    }
function clipboardInit () {
      outline.clipboard = {}
      outline.clipboard.objects = []
      outline.clipboard.predicates = []
      outline.clipboard.all = []
    }
/* clipboard principle: copy wildly, paste carefully
ToDoS:
1. register Subcollection?
2. copy from more than one selectedTd: 1.sequece 2.collection
3. make a clipboard class?