doc: mention how to avoid newlines impacting ls -1

* src/ls.c (usage): Mention the -b and -q options
in the -1 description.
* doc/coreutils.texi (ls invocation): Likewise.
tests: add a case verifying mv on case insensitive file systems

* NEWS: Update the recent entry to also mention the avoidance
of incorrectly unlinking a multi-hardlinked "source" file when
presented with source and dest that only differ in case.
* src/copy.c (same_file_ok): Mention the case issue with same_name().
* tests/mv/hardlink-case.sh: Test the issue on HFS+.
* tests/local.mk: Reference the new test case.
* tests/mv/vfat: Remove an old related but unused test case.