Added support for multi-value variables.

Example:
	var (x, *y) = (1, 2, 3);   # x=1 and y=[2, 3]

This also works for functions:

func f(a, *b) {
   say "#{a}, #{b.dump}";
}

f(1);       # => 1, []
f(1, 2);    # => 1, [2]
f(1, 2, 3); # => 1, [2, 3]