* doc/tar.1: Add missing dots, use plural when necessary,
tweak a wording. Remove an incorrect observation, three times.
Add some missing articles, correct some formatting,
and expand the opaque descriptions of two options.
* doc/tar.texi: Drop a stray `cd` command from an example.
Correct two cross references, correct the paragraph
about the manpage, and unbreak a URL.
* src/names.c: Correct and shorten an error message: "non-optional"
means "mandatory", but "non-option" is what was meant. And the
phrase "in archive create or update mode" was both unneeded and
incomplete.
* tests/positional01.at: Change expected error text.
* tests/positional02.at: Likewise.
* tests/positional03.at: Likewise.
* src/create.c (dump_file0): For clarity, change diagnostic
wording from "file is the archive; not dumped" to "archive cannot
contain itself; not dumped". All test cases and documentation changed.
* src/names.c (file_selection_option)
(file_selection_option_name): New functions.
(unconsumed_option_push, unconsumed_option_free)
(unconsumed_option_report): New functions.
(name_list_advance): Maintain a list
of eventually unconsumed options during archive creation.
Report unconsumed options, if any.
* tests/positional01.at: New test case.
* tests/positional02.at: New test case.
* tests/positional03.at: New test case.
* tests/Makefile.am: Add new test cases.
* tests/testsuite.at: Likewise.
* NEWS: Document the changes.
* configure.ac: Version 1.29.90
* doc/tar.texi: Document the changes.
