DateTimeException if the two intervals do
not intersect or if the given interval is empty.
Example: -------------------- assert(NegInfInterval!Date(Date(2012, 3, 1)).intersection( Interval!Date(Date(1990, 7, 6), Date(2000, 8, 2))) == Interval!Date(Date(1990, 7 , 6), Date(2000, 8, 2)));
assert(NegInfInterval!Date(Date(2012, 3, 1)).intersection( Interval!Date(Date(1999, 1, 12), Date(2015, 9, 2))) == Interval!Date(Date(1999, 1 , 12), Date(2012, 3, 1))); --------------------