Fix double mappings handling and expand trailing paragraph marker definition

[Enkidu93]

Fixes #517, #518.

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This change is 

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.34%. Comparing base (b240b7b) to head (52463f3).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #521      +/-   ##
==========================================
+ Coverage   74.33%   74.34%   +0.01%     
==========================================
  Files         456      456              
  Lines       38249    38261      +12     
  Branches     5237     5242       +5     
==========================================
+ Hits        28432    28445      +13     
  Misses       8666     8666              
+ Partials     1151     1150       -1     

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[ddaspit]

I pushed two fixes.

@ddaspit reviewed 2 files and all commit messages, and made 2 comments.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on Enkidu93 and pmachapman).

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tests/SIL.Machine.Tests/Corpora/ConvertUsfmVersificationHandlerTests.cs line 977 at r3 (raw file):

        string[] targetLines = target.Split('\n');
        string[] truthLines = truth.Split('\n');
        // Assert.That(targetLines.Length, Is.EqualTo(truthLines.Length));

Nit: did you mean to comment this out?

[pmachapman]

This worked well for my test projects.

@pmachapman reviewed 2 files and all commit messages, and made 1 comment.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on Enkidu93).