Filing a "method shadows local" scoping bug

This bug is similar to the one that Kyle filed in
test/functions/kbrady/proc_scoping.chpl in which a
(compiler-generated?) method from a standard/internal module is
shadowing a local variable.  Intuitively, it seems to me that methods
should never do this, suggesting scoping is broken.  Somewhat
maddeningly, I've been unable to determine (in the time I've spent on
it so far) the root cause of the shadowing symbol.  See the .future
for further details.
Moved 'use' of FileSystem to a more logical, but artificially scoped place

On Lydia's request, moved 'use' of FileSystem into a closer scope and
removed the fully-qualified references to isDir(), isFile(), isLink().
Added a comment explaining the use of the scope and referring to the
future I just filed.