Implement tuples, needed to export per-CPU scheduling data.

Implement tuples, needed to export per-CPU scheduling data.

It is now possible to save and print immutable arrays as below:

..$t = (1, 42, "something");
..printf("%d %s\n", $t.1, $t.2);

Also add support for evaluating builtin in order to save them in variables
(required by tuples)