Fix doc warnings

See merge request gkiagia/wireplumber!19

This allows linking the client to the stream that has the same name
as the role that it requests.

It so happens that sometimes the client proxy is created and destroyed
immediately, almost instantly, which causes this code to crash in case
the proxy pointer is gone when our idle callback tries to destroy it.

This change makes the whole operation safe.

Stop client

See merge request gkiagia/wireplumber!18

See merge request !16

Currently, the stream names have to be duplicated in the configuration
file. This is going to change in a future version.

... and simplify some code there

This is currently the documented way of describing controls
that have an effect on all streams

simple-endpoint-link: dont link already linked ports

See merge request gkiagia/wireplumber!17

Async endpoint links

See merge request gkiagia/wireplumber!15

If we have properties, strtok will return strings from there as tokens
and the error will appear later as we will attempt to parse an incomplete
GVariant. It is better to catch this early so that we can print a more
useful error message.

So now we can do:
---
load-module C foo {
  "property": <"value">
}
---

The starting brace is still required to be on the same line
as the load-module.

Properties are expected to be a GVariant a{sv} dictionary,
specified in the GVariant text format:
https://developer.gnome.org/glib/stable/gvariant-text.html

Unregister fixes

See merge request gkiagia/wireplumber!14