More tests for the position function.  Theses tests demonstrate failure when position is passed a list that is not a proper list and the item does not exist in the list.
More tests for the position function.  Theses tests demonstrate
failure when position is passed a list that is not a proper list
and the item does not exist in the list.

Added comments indicatiting places where tests should not be added, in
addition to preivous comments indicating where tests *should* be
added.

clasp-developers/SICL,clasp-developers/SICL,clasp-developers/SICL,vtomole/SICL,vtomole/SICL,vtomole/SICL,clasp-developers/SICL,vtomole/SICL