Enhance codebase line/branch coverage

[poyenc]

The goal of code coverage is 90%

[codecov]

Codecov Report

Merging #17 into develop will increase coverage by 21.97%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##           develop      #17       +/-   ##
============================================
+ Coverage    70.95%   92.92%   +21.97%     
============================================
  Files            3        3               
  Lines          210      212        +2     
  Branches        74       66        -8     
============================================
+ Hits           149      197       +48     
+ Misses          18        0       -18     
+ Partials        43       15       -28     

Impacted Files	Coverage Δ
include/boost/token_iterator.hpp	92.30% <ø> (+21.93%)	⬆️
include/boost/token_functions.hpp	93.33% <100.00%> (+22.14%)	⬆️
include/boost/tokenizer.hpp	83.33% <0.00%> (+16.66%)	⬆️

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[aminya]

Could you break your changes into multiple commits? Each change should have a rational in their commit message.

The commit which adds the tests is OK.

[jeking3]

Please rebase and only include the test code changes, not the changes from #18. When I tried to do this I got four test failures.