Hide option on /configservice if not supported

Minor cleanup of icon set selector

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

Switch Snark dark and light themes to using images embedded in the .war, and remove the images substitutions from the filesystem and css

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

snark theme fixes: Revert the i2psnark buttons on the ubergine and vanilla themes back to their original versions, but keep flat buttons for dark and light themes. Fix some squashed icons and apply some slightly better icons for indicating torrent status and contents on dark theme.

Show current setting for owndest in CLI
Skip a irrelevant log message for I2Ping
Break wait on interrupt
Log level tweaks

just adds clutter with no value.
Change last-changed time on leaseset debug page to use standard formatting

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

HTTP, IRC, and Streamr servers
IRC, SOCKS IRC, and Streamr clients

WIP - full blocking requires restart for now

Appx. 38% speedup
As suggested by jogger

from a geoip 1 or 2 database,
to prep for a country blocklist (ticket #2759)
WIP - not hooked in yet

Adjust synchronization
Fix logging for feed file
Prep for a country blocklist (ticket #2759 WIP)