xgettext: Add Ruby support.

xgettext: Add Ruby support.

* gettext-tools/src/x-ruby.h: New file.
* gettext-tools/src/x-ruby.c: New file.
* gettext-tools/src/xgettext.h (verbose): New declaration.
* gettext-tools/src/xgettext.c: Include x-ruby.h.
(verbose): New declaration.
(flag_table_ruby): New variable.
(long_options): Add '--verbose'.
(main): Update for Ruby. Handle '-v'/'--verbose' option.
(usage): Document the '-L Ruby' and '-v' options.
(xgettext_record_flag, language_to_extractor, extension_to_language): Update for
Ruby.
* gettext-tools/src/Makefile.am (noinst_HEADERS): Add x-ruby.h.
(xgettext_SOURCES): Add x-ruby.c.
* gettext-tools/src/FILES: Mention x-ruby.h, x-ruby.c.
* gettext-tools/tests/xgettext-ruby-1: New file.
* gettext-tools/tests/format-ruby-1: New file.
* gettext-tools/tests/format-ruby-2: New file.
* gettext-tools/tests/Makefile.am (TESTS): Add them.
* gettext-tools/doc/gettext.texi (Ruby): New section.
* gettext-tools/doc/xgettext.texi: Document the '-L Ruby' and '-v' options.
* HACKING: Document the recommended Ruby packages.
* NEWS: Mention the Ruby support.