Implement for loops

[omdxp]

Is your feature request related to a problem? Please describe.
There are no for loops at the moment.

Describe the solution you'd like
Implement for loops for more sophisticated and readable code.

Additional context
Potential sample code:

// for range
for i : 0..10 {
  printf("%d\n", i);
}

// for array
num[] arr = [1, 2, 3];
for item : arr {
  printf("%d\n", item);
}

for i, item :: arr {
  printf("arr[%d]=%d\n", i, item);
}