Add a multilocale test for chdir/cwd().

Suggested by Michael.  Multi-task one is next.
Update the comments on chdir and cwd to represent their behavior in multilocale
situations.
Add a test to lock in the behavior of chdir and cwd in a parallel environment.
Merge branch 'master' into multilocaleChdirTesting
Add comments to chdir() and cwd() indicating behavior in a parallel environment.

Within a single locale, calls to chdir() from a single task will affect the
output of cwd() for all tasks.
Merge pull request #461 from lydia-duncan/multilocaleChdirTesting

Multilocale chdir testing

Add two tests of the chdir()/cwd() functionality. The first test locks in the
behavior in a multilocale context; chdir() calls on one locale will not
affect cwd() calls on a different locale. The second test indicates
behavior in a single locale/multiple tasks environment; chdir() calls
from one task will affect cwd() calls in a different task on the same
locale.

This behavior is now indicated in the comments for these functions.