fixes #198 negative send/receive deadlines do not work

[gdamore]

This actually affected pretty much all the protocols and both send
and receive deadlines. While here we've also made sure that
a non-blocking check will not fail if a message can immediately
be sent or received.

[codecov]

Codecov Report

❌ Patch coverage is 98.30508% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 99.61%. Comparing base (e0b0da2) to head (4d69051).
⚠️ Report is 79 commits behind head on main.

Files with missing lines	Patch %	Lines
protocol/xbus/xbus.go	85.71%	1 Missing and 1 partial ⚠️
protocol/xreq/xreq.go	91.66%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##              main     #216      +/-   ##
===========================================
- Coverage   100.00%   99.61%   -0.39%     
===========================================
  Files           46       43       -3     
  Lines         6584     4978    -1606     
===========================================
- Hits          6584     4959    -1625     
- Misses           0       15      +15     
- Partials         0        4       +4     

Flag	Coverage Δ
unittests	99.61% <98.30%> (-0.39%)	⬇️

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