Added the option to the command line to set the number of extra lines in code snippets

[JustMisha]

Type: feature
Breaking change: no

Instead of the magic number "2" in the renderReport method in the HTMLRenderer class, the protected field extraLineInExcerpt has been added, which is 2 by default and can be set using the --extra-line-in-excerpt command line argument.

[AJenbo]

I think you need to adjust the tests:

ArgumentCountError: Too few arguments to function PHPMD\Renderer\HTMLRenderer::__construct(), 0 passed in C:\projects\phpmd\src\test\php\PHPMD\Renderer\HTMLRendererTest.php on line 52 and exactly 1 expected
C:\projects\phpmd\src\main\php\PHPMD\Renderer\HTMLRenderer.php:73
C:\projects\phpmd\src\test\php\PHPMD\Renderer\HTMLRendererTest.php:52
phpvfscomposer://C:\projects\phpmd\vendor\phpunit\phpunit\phpunit:51

[JustMisha]

Not to change the tests, made the $extraLineInExcerpt argument optional in the __constructor. This seems to make more sense.

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.02% 🎉

Comparison is base (63ca48a) 92.37% compared to head (c4484f1) 92.39%.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #1029      +/-   ##
============================================
+ Coverage     92.37%   92.39%   +0.02%     
- Complexity     1215     1220       +5     
============================================
  Files           110      110              
  Lines          3331     3342      +11     
============================================
+ Hits           3077     3088      +11     
  Misses          254      254              

Files Changed	Coverage Δ
src/main/php/PHPMD/Renderer/HTMLRenderer.php	87.68% <100.00%> (+0.36%)	⬆️
src/main/php/PHPMD/TextUI/CommandLineOptions.php	100.00% <100.00%> (ø)

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[tvbeek]

@JustMisha Thanks for this PR, this is a nice addition. And with using an optional parameter in the constructor you also catch any BC like option of someone use the class on a not suspected way.