Add UNRAVEL , dumps call stack

[philburk]

Fixes #193

[robzed]

I haven't tested these, but they look similar enough to my tests to approve.

[robzed]

Did a quick test on the Unravel branch. Everything looks ok to me. (This is 64-bit M2 MBP)
(Branch) * unravel 8921d00 Add UNRAVEL , dumps call stack

Standalone pForth executable written to pforth_standalone
rob@MacBook-Pro unix % ./pforth_standalone
PForth V2.1.1, LE, built Jan 13 2025 19:30:17 (static)
: test 1234 unravel ; ok
Stack<10>
test
Calling sequence:
TEST
ok
Stack<10> 1234
: test2 998 test ; TEST2 redefined.
ok
Stack<10> 1234
test2
Calling sequence:
TEST TEST2
ok
Stack<10> 1234 998 1234
: test3 2 3 4 test2 ." hello" ; ok
Stack<10> 1234 998 1234
test3
Calling sequence:
TEST TEST2 TEST3
hello ok
Stack<10> 1234 998 1234 2 3 4 998 1234