Because we need to catch errors that are caused by a borken pipe when
writing to stdout (for example), this patch changes the interface of the
Viewer trait to return an error enum that can be used to check whether
an IO error happened.
The calling code can then decide whether to ignore a broken pipe error
or whether to handle it properly.
Signed-off-by: Matthias Beyer <mail@beyermatthias.de>
In the previous versions, the sink (where the entries should be written
to) was not passed.
This did conflict with the libimagrt holding the stdout/stderr handles,
because it automatically writes to stdout (which we don't want to do in
some cases).
Passing the sink is way nicer. This patch changes libimagentryview so
that the sink is passed to the viewer.
