doc/texi2pod.pl: drop unnecessary rule, which was converting "\," to ","

I cannot find a reason for such a rule, which was resulting in badly
escaped filtergraph snippets.

Fix trac ticket #1610.
(cherry picked from commit ce875a613a16b06b0a561774955111f7a24d12bb)

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
doc/texi2pod: recognize @table @command.
(cherry picked from commit ee2d6fbc92e6d55dda319fa56234c5be9a476728)

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
doc/texi2pod: add support to @ifhtml and @ifnothtml directives

With these commands it is possible to add HTML and non-HTML snippets,
which will be useful for the "See Also" manual chapters.
(cherry picked from commit f14e248783f45a698947a2ed6e2c82069db46bc8)

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
doc/texi2pod: correctly handle @url commands in the form @url{URL,...}

Ignore the other arguments, which have not to be processed by the POD
renderer.
(cherry picked from commit 1f9855dbc1102e63fa7ce932d0edf0d545c89b09)

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
doc/texipod: add rule to correctly interpret @ref{ANCHOR,XREF,SECTION_NAME,...}

This allows to name an internal reference in the POD/MAN output.
(cherry picked from commit c499d45c6bea8d7bbbb7a819c53fe9766136bf29)

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
doc: support multitable in texi2pod
(cherry picked from commit 5ea5ffc9cee1b91eed471fff2f51d771222cf8d2)

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
doc/texi2pod: fix warnings introduced in e7e14bc69a606a6bec82efef729263cd38f122d4

The variable "$section" was replaced by "$chapter".
(cherry picked from commit c0c06c1bba80c4bee162a3c40eec678ddc65571d)

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
doc/texi2pod: fix @ref substitution rule, disallow "}" within the fields

Fix potential spurious substitution.
(cherry picked from commit 9167db3829f360f241255d4240ba6b7135ab4111)

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
doc/texi2pod: rework man inclusion logic

Ignore @c man begin ... @c man end comments, rely on @chapter for marking
the beginning of the various manual top level sections.

This allows us to write markup which is not dependent on the specific
texi2pod.pl implementation.

This change causes a few rendering issues, which will be fixed in further
patches.
(cherry picked from commit ca3d786227adf20f4e19809090c980d6d1109bf8)

Signed-off-by: Timothy Gu <timothygu99@gmail.com>
doc/texi2pod.pl: skip printing chapter names if they are disabled
(cherry picked from commit c838701ce4515bd51f7827be0b20f256ba5c69f3)

Signed-off-by: Timothy Gu <timothygu99@gmail.com>