Fixes to prototype nap detection functionality and bug in missing sleeplog handling

[vincentvanhees]

This PR includes:

• Fix to minor bug Missing night in sleeplog causes last night to be ignored #686 closes Missing night in sleeplog causes last night to be ignored #686
• Minor fixes to prototype nap detection functionality Facilitate methodological research on self-reported nap/nonwear aggreement with acc based rest (sustained inactivity bout) classification #687

Checklist before merging:

• Existing tests still work (check by running the test suite, e.g. from RStudio).
• Added tests (if you added functionality) or fixed existing test (if you fixed a bug).
• Updated or expanded the documentation.
• Updated release notes in inst/NEWS.Rd with a user-readable summary. Please, include references to relevant issues or PR discussions.
• Added your name to the contributors lists in the DESCRIPTION and CITATION.cff files.

[codecov-commenter]

Codecov Report

Merging #688 (27df28a) into master (f4e8b91) will increase coverage by 0.00%.
The diff coverage is 100.00%.

❗ Current head 27df28a differs from pull request most recent head 92f4b78. Consider uploading reports for the commit 92f4b78 to get more accurate results

@@           Coverage Diff           @@
##           master     #688   +/-   ##
=======================================
  Coverage   73.25%   73.25%           
=======================================
  Files          87       87           
  Lines       10744    10746    +2     
=======================================
+ Hits         7870     7872    +2     
  Misses       2874     2874           

Impacted Files	Coverage Δ
R/g.part5.R	73.85% <ø> (ø)
R/g.part4.R	73.78% <100.00%> (ø)
R/g.part5.classifyNaps.R	90.90% <100.00%> (+0.28%)	⬆️
R/g.sibreport.R	91.02% <100.00%> (+0.11%)	⬆️

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

[vincentvanhees]

@jhmigueles these are bug fixes in very specific use-cases, so unlikely to cause problems with normal GGIR behaviour. Are you ok if I merge this?

[jhmigueles]

I've run this branch in some files and cannot see any problem. Let me know if you want me to look at anything specifically, otherwise I think you can merge =)