doc: make all manpages with Doxygen

Use (fixed-up) Doxygen manpage output for all program & module manpages.

This also allows formatting the manual pages properly in the HTML docs.

The Markdown pages work properly only with Doxygen >= 1.9.7, older
versions put them to wrong place in the HTML docs.

doc/dox/programs/pw-metadata.1.md

@@ -0,0 +1,73 @@
+\page page_man_pw-metadata_1 pw-metadata
+
+The PipeWire metadata
+
+# SYNOPSIS
+
+**pw-metadata** \[*options*\] \[*id* \[*key* \[*value* \[*type* \] \] \] \]
+
+# DESCRIPTION
+
+Monitor, set and delete metadata on PipeWire objects.
+
+Metadata are key/type/value triplets attached to objects identified by
+*id*. The metadata is shared between all applications binding to the
+same metadata object. When an object is destroyed, all its metadata is
+automatically removed.
+
+When no *value* is given, **pw-metadata** will query and log the
+metadata matching the optional arguments *id* and *key*. Without any
+arguments, all metadata is displayed.
+
+When *value* is given, **pw-metadata** will set the metadata for *id*
+and *key* to *value* and an optional *type*.
+
+# OPTIONS
+
+\par -r | \--remote=NAME
+The name the remote instance to use. If left unspecified, a connection
+is made to the default PipeWire instance.
+
+\par -h | \--help
+Show help.
+
+\par \--version
+Show version information.
+
+\par -l | \--list
+List available metadata objects
+
+\par -m | \--monitor
+Keeps running and log the changes to the metadata.
+
+\par -d | \--delete
+Delete all metadata for *id* or for the specified *key* of object *id*.
+Without any option, all metadata is removed.
+
+\par -n | \--name
+Metadata name (Default: "default").
+
+# EXAMPLES
+
+**pw-metadata**
+
+Show metadata in default name.
+
+**pw-metadata** -n settings 0
+
+Display settings.
+
+**pw-metadata** -n settings 0 clock.quantum 1024
+
+Change clock.quantum to 1024.
+
+# AUTHORS
+
+The PipeWire Developers <$(PACKAGE_BUGREPORT)>;
+PipeWire is available from <$(PACKAGE_URL)>
+
+# SEE ALSO
+
+\ref page_man_pipewire_1 "pipewire(1)",
+\ref page_man_pw-mon_1 "pw-mon(1)",
+\ref page_man_pw-cli_1 "pw-cli(1)",