Options to control option handling in file lists.

The --verbatim-files-from option disables option handling in
file lists.  The --no-verbatim-files-from reverts its effect.

The --null option implies --verbatim-files-from.  This restores
the documented behavior, broken by 26538c9b.

* src/common.h (verbatim_files_from_option): New global.
* src/names.c (name_elt): New member: file.verbatim
(name_add_file): Take 'verbatim' state as its third parameter.
(read_next_name): Don't call handle_option if file.verbatim
is set.
* src/tar.c: New options --verbatim-files-from and
--no-verbatim-files-from.

* doc/tar.texi: Document --verbatim-files-from and
--no-verbatim-files-from options.
* NEWS: Update.
* configure.ac: Version 1.28.90

* tests/T-null2.at: New testcase.
* tests/Makefile.am: Update.
* tests/testsuite.at: Update.