optparse: sync with upstream.

* lib/specl/optparse.lua: Sync with upstream for latest fixes.
* specs/optparse_spec.yaml: Remove.  No longer owned by this
project.
* specs/specs.mk (specl_SPECS): Remove optparse_specl.yaml.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>
specl: support file:NN:EE format line filters in arguments.

* specs/spec_helper.lua (run_spec): Only add the "-" argument
when params.stdin is set.
(Tmpfile): Remove unnecessary __tostring metamethod.
* specs/specl_spec.yaml: Add specifications for behaviour with
various combinations of +NN and :NN:EE arguments, and rearrange
into contexts for readability.
* lib/main.lua (process_args): Accept line number filters as :NN
or :NN:EE suffixes to filenames.
(OptionParser): Update help text.
* doc/specl.md (Command line): Update.
* NEWS: Update.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>