server/reds.c: spice_printerr cleanup
server/reds.c: spice_printerr cleanup

Rules for replacing spice_printerr:
* if it's a client drop / agent drop, spice_error
* if it's important, spice_warning
* else, spice_info.

The fourth rule is spice_debug if it's going to fill up the log, but
nothing of the sort here.

Other things this patch does:
* changed reds_show_new_channel to reds_info_new_channel in an attempt to
advertise it doesn't always show anything, unless SPICE_DEBUG_LOG_LEVEL
>= SPICE_DEVUG_LOG_INFO (==3)
* removes two lines of whitespace.
* added "crashy" to multiple client warning (only warning introduced,
  the rest are errors).

freedesktop-unofficial-mirror/spice__spice,alon/spice-server,dezelin/spice,mathslinux/spice,mathslinux/spice,SPICE/spice,mathslinux/spice,fgouget/spice,alon/spice-server,freedesktop-unofficial-mirror/spice__spice,ya-mouse/spice,dezelin/spice,SPICE/spice,freedesktop-unofficial-mirror/spice__spice,dezelin/spice,elmarco/spice,elmarco/spice,Fantu/spice,freedesktop-unofficial-mirror/spice__spice,Fantu/spice,Fantu/spice,alon/spice-server,ya-mouse/spice,SPICE/spice,dezelin/spice,fgouget/spice,alon/spice-server,alon/spice-server,freedesktop-unofficial-mirror/spice__spice,mathslinux/spice,Fantu/spice,dezelin/spice,mathslinux/spice,elmarco/spice,elmarco/spice,ya-mouse/spice,fgouget/spice,elmarco/spice,fgouget/spice