Merge pull request #1252 from c-rack/master

Problem: return code of sodium_init() is not checked.
use more conservative 30 second default timeout for LINGER

Regression in #1248 can cause lost messages at exit.
Merge pull request #1253 from minrk/linger-timeout

use more conservative 30 second default timeout for LINGER
Fix busy-polling bug in pgm_sender causing it to consume CPU cycles
Re-enable pollout before cancelling tx timeout
Merge pull request #1255 from klaussfreire/master

Fix busy-polling when reaching the rate limit