Virtual devices tend to start with partial fields set in the EnumFormat
param (usually rate is missing). This causes virtual devices to be
invisible until they are used in some way.
Fix this by relaxing the parsing of EnumFormat and by falling back to
the server defaults for the unspecified fields.
Fixes#1413
When a sink is RUNNING but there is nothing linked to the input it must
be the monitor that is keeping it active, report IDLE for the sink in
that case.
When a source is RUNNING but there is nothing linked to the output it
must be the sink part that is keeping it active, report IDLE for the
source.
Fixes#1345
