Add a parser 'virtual' object in SWIG interface

* tta/C/main/document_types.h (PARSER): add struct in this file to
hide it from the SWIG interface.  It only holds a parser configuration
descriptor.

* tta/C/main/parser_conf.c (unregister_parser_conf_descriptor): add.

* tta/C/Makefile.am (C_libtexinfo_main_sources),
tta/C/swig/swig_parser_api.c (txi_ext_parser, txi_ext_destroy_parser)
(txi_ext_parse_*, txi_ext_parser_conf_*), tta/swig/perl/Makefile.am
(SWIG_header_dependencies): add an interface for parse_* and
parser_conf_* with a constructor and a desstructor and parser in
argument, that allows to find associated parser conf and apply conf.

* tta/swig/perl/parse_refold.pl, tta/swig/perl/t/*.t,
tta/swig/python/test_Texinfo.py, tta/swig/texinfo.i (parse_*)
(parser_conf_*): use interface with a parser.
16 files changed