thorium: add function to check traffic

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
thorium_worker: add function to check traffic

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
message_multiplexer: don't flush if the outbound link is not saturated

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
thorium: lower the multiplexer timeout to 100 microseconds

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
thorium: increase maximum allowed throughput

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>