If the 'HardenedValidations' amendment is enabled, this commit will
track the version of the software that validators embed in their
validations.
If a server notices that at least 60% of the validators on its UNL
are running a newer version than it is running, it will periodically
print an informational message, reminding the operator to check for
update.
This commit restructures the HTTP based protocol negotiation that `rippled`
executes and introduces support for negotiation of compression for peer
links which, if implemented, should result in significant bandwidth savings
for some server roles.
This commit also introduces the new `[network_id]` configuration option
that administrators can use to specify which network the server is part of
and intends to join. This makes it possible for servers from different
networks to drop the link early.
The changeset also improves the log messages generated when negotiation
of a peer link upgrade fails. In the past, no useful information would
be logged, making it more difficult for admins to troubleshoot errors.
This commit also fixes RIPD-237 and RIPD-451
