use more meaningful messages for runnning tests
add method to tell peers about own state

this will be used by [netpd-find-sync] in order to optimize
the find-sync-peer protocol
improved find-sync-peer protocol

tries to fix situation where some clients assumed to be alone (timeout expired)
and thus set themselves 'ready', so they propagated their wrong states to other
peers.

if there are peers around who already found a sync peer, but are not yet ready
the timeout will be increased and if it expires then, a new request is sent. Only
if there is no response at all, it is assumed that no other peers around and only
then it is assumed valid to set itself to 'ready'.
add description about how to reliably find a sync peer
remove too verbose 'test' message
restore connections in [pd unpatch_sync]

this was only changed to perform some test and got erraneously commited
bump unpatch version to 2.1.0
fix chat click for pd >= 0.44
add mutex lock to allow many concurrent instances