light: fix zero progress of rate display
marsadm: fix forgotten unlinks in {invalidate,leave-resource}
marsadm: fix split brain prevention on handover
marsadm: start 'primary' handover after fetch has completed
net: fix unnecessary socket shutdown on nonblocking connects
light: fix long-lasting pause-fetch effect
infra: move io_timeout to generic interface

This is needed for the next commit.
light: fix client shutdown on slow network

On slow networks, the generic net_io_timeout is too long if you are
impatiently waiting for disconnect.

Change the io_timeout of the individual client brick to a short value.
light: fix copy switch off
net: fix long-lasting disconnects, abort send/recv in realtime

Use realtime units (seconds) for aborting network operations.
This is important for some operations when the network has an
extreme bottleneck.