Comment 1 for bug 1010850

Update (for reference): I have solved my problems using method 4 (above), with the small python function below. So I'm happy. Problems 1 and 3 may still be worth fixing, though.
==

def delta(V, pt):
    """Unit area delta function in discrete space V"""
    q = Function(V)
    PointSource(V, pt).apply(q.vector())
    q /= assemble(q*dx)
    return q

...
q_s = delta(S, Point(0.0))