Port changes from sillsdev/machine.py#336

[pmachapman]

Fixes #487

The only real changes I could see that needed porting from sillsdev/machine.py#336 were in AlignedWordPair.ToString(), and the unit tests for Flatten().

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This change is 

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.72%. Comparing base (b42b452) to head (c0942a9).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #498      +/-   ##
==========================================
+ Coverage   73.66%   73.72%   +0.05%     
==========================================
  Files         452      452              
  Lines       37925    37925              
  Branches     5210     5210              
==========================================
+ Hits        27938    27960      +22     
+ Misses       8842     8818      -24     
- Partials     1145     1147       +2     

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[ddaspit]

@ddaspit reviewed 3 files and all commit messages, and made 1 comment.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on Enkidu93).

[Enkidu93]

That sounds right to me. Thanks, Peter!

@Enkidu93 reviewed 3 files and all commit messages, and made 1 comment.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on pmachapman).