to prevent failures on connections esp. for hidden mode

Set accurate lengths for zero-copy

WIP, to be hooked in

Store back ref to controller in tunnel
Stop server controller on I2PException
Support generation of keys with fractional days expiration for testing

Remove ratchet tag from RSKM on timeout

Additional checks on ECIES BRR to catch old/buggy routers
Detailed logging of ECIES BRR decrypt fails

to save space; not stored for participating tunnels.

modelled on TCP Reno (RFCs 5681 and 6298)
- Use a single timer per connection
- Resend up to half the un-acked messages per timer event instead of a single message
- Only send either old or new messages, do not mix
- Cache/avoid several timer calls
- Instead of 3 return values, allocating bandwidth is now a boolean function
- Avoid one of the iterations over all un-acked messages every packet pusher loop
- Remove 100 ms failsafe
- Fix OMF debug log NPE
With the same cpu usage the bandwidth is much higher
Significant speed improvement for lossy connections (e.g. wifi)
Patch by zlatinb

Support sending encrypted lookups and stores to ECIES routers
Support requesting AEAD replies to ECIES routers
Encrypt RI lookups when using ECIES even on slow machines
Switch back to RatchetSKM
Don't schedule ack timer for router SKM
Reduce getContext() calls
GMB null check cleanup
MessageWrapper javadoc clarifications
Log tweaks

patch from zlatinb

NetDB parts still TODO
Remove PK param from GMB.buildECIESMessage(), already in config

- StatisticsManager fix for null router in unit tests
- Debug toString() enhancements
- Dest hash logs in b32
- Javadoc fix

http://zzz.i2p/topics/2968

reject reserved ranges

Hide sessions with null public key

Don't use non-ElGamal routers for lookups or stores
Prevent DSA-SHA1 routers from auto-floodfill

Ant version 1.9.8 or higher now required
Drop support for Xenial package build
Fix up BOB build configuration
Fix i2psnark standalone build

Preliminary, proposal not finalized, subject to change
Not yet compatibility tested with other implementations
Add peers to match requested length for explicitPeers
remove commented out code
log tweaks

Add support for zen and zen2
Enable more fallbacks for zen and zen2
Adds Zen and Zen2 binaries, stripped
Built with gcc 9.3.0
Other binaries will be added if testing shows improvement
Fix hangs in mbuild-all.sh build script
Add silvermont and goldmont to build script, untested, support TBD
GMP is GPLv2
More info: http://zzz.i2p/topics/2955