Fix: zero out data structure before using it

Fixes #716

Signed-off-by: David Goulet <dgoulet@efficios.com>
Fix: send the streams sent message after metadata

We now make sure that we only sent the streams_sent message to the relay
when all the streams (including the metadata) are sent.

Signed-off-by: Julien Desfossez <jdesfossez@efficios.com>
Signed-off-by: David Goulet <dgoulet@efficios.com>
Fix: notify the viewer if new streams got added

As soon as new streams are available, the viewer must start reading
them, otherwise we risk to ignore complete streams.

Signed-off-by: Julien Desfossez <jdesfossez@efficios.com>
Signed-off-by: David Goulet <dgoulet@efficios.com>