bump version to 0.5.6-r3

Re-added and corrected bernds fix - it does not need ntohl in ipc

Revert bernds patch do too much differences I cannot see the real changes :(

Fixed an embarrassing bug if we want to generate a netmask from a prefix == 0.
Added an inline function to avoid someone else making the same mistake

All credits belong to Markus Kittenberger <Markus.Kittenberger@gmx.at> for finding,
reporting and hunting it down to the root cause.

Fix Win32 compile errors

Restore ability of message handlers to discard forwarding

bugfix: do a proper list merging of the temporary timer list

bugfix timer bucket walk:
while walking a timer bucket it may happen that due to a stopped timer
killing other timers we may loose our walking context.
dequeue all timer entries to a temporary queue and mount it back at the end.
Idea inspired on a email exchange with Bernd Petrovitsch <bernd@firmix.at>

Remove stray debug

Reparied picky duplicate filter