log tweaks

NetDb: Drop all-zero lookups and stores, add stats
SSU:
 - Fix debug logging of dumped packets
 - Drop sessions with bad clock skew, banlist peer, add stats
 - Drop sessions with corrupt DSM, banlist peer, add stats
Log tweaks

Thanks parg!

isn't destroyed and immediately replaced by i2ptunnel,
which caused dup shared clients in a race at startup;
Clarify session exception text if not open

(treat INIT as CLOSED) better fix to follow

isn't treated as CLOSED and immediately replaced by i2ptunnel,
which caused dup shared clients in a race at startup
(possible related tickets #642, #650, #815, #1545)

Instead of enabling exceptions when needed for custom set-ups, some users will
opt for disabling all security functions.

Synchronize UDPPacket methods, possible fix for bad
packets and UDP stalls caused by cache corruption?
Cleanup unused methods and fields

     and '67eb724b7638284d33f1b4997183cc9f197d2883'

doh

Fix name and URL escaping
Truncate long URLs in display