sift keys by predicate
generalize "zero Mul of args must contain zero"
add Q.infinity(Add(args)) <==> any(map(Q.infinity, args))
Merge branch 'newassump' of github.com:asmeurer/sympy into newassump

Conflicts:
	sympy/assumptions/newask.py
Merge pull request #51 from mrocklin/newassump

Newassump