Add support for .rsj files.
* gettext-tools/src/x-rst.h (EXTENSIONS_RST, SCANNERS_RST): Add RSJ scanner.
(extract_rsj): New declaration.
* gettext-tools/src/x-rst.c: Implement extraction from .rsj files.
* gettext-tools/src/xgettext.c (usage): Mention RSJ along with RST.
* gettext-tools/tests/xgettext-rst-1: New file.
* gettext-tools/tests/xgettext-rst-2: New file.
* gettext-tools/tests/Makefile.am (TESTS): Add them.
* gettext-tools/tests/lang-pascal: Extract from .rsj file, if the compiler
generated it.
* gettext-tools/doc/gettext.texi (RST): Mention that .rsj files are supported
as well.
* gettext-tools/doc/xgettext.texi (Choice of input file language): Mention RSJ
along with RST.
* NEWS: Mention the change.
