* Move connection checkin log messages to their own target

Under heavy load they can happen thousands of times per second, and
should generally be considered a nuisance at best. This marks the state
discard as an info rather than a warning, and moves all the messages
into their own log-target, so they can be filtered separately from the
more relevant warnings.

Signed-off-by: D.S. Ljungmark <spider@skuggor.se>

* Remove left-over env_logger dependencies

When moving to tracing-subscriber for logging, the env_logger
dependencies were left around, this cuts them out as dead code.

Signed-off-by: D.S. Ljungmark <spider@skuggor.se>

* Restore ability to filter log messages at runtime

This restores the RUST_LOG filters from env_logger but now with the
tracing subscriber setup. The filters are chained so commandline options
mark the default in case either option is set, which should be the path
of least confusion for users.  ( RUST_LOG setting level to debug, and
commandline to warning is an odd user case, and I don't know what a user
who does that is expecting. )

It also bumps the version number as a fix to see which versions have
which behaviour.

Signed-off-by: D.S. Ljungmark <spider@skuggor.se>

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Signed-off-by: D.S. Ljungmark <spider@skuggor.se>