Additions to the Perl family of languages (#4066)

* Mainly fixing problems with Perl heuristics

And also adding a little bit of text to the README file to help with local use and test.

* Adds new sample

* Adds a couple of samples more, not represented before

* Moves installation intructions to CONTRIBUTING.md

Refs #2309 and also changes github.com to an uniform capitalization.

* Correcting error. Great job, CI

* Moving another file

* Adds samples and new checks for perl/perl6

* Stupid mistake

* Changing regex for perl5 vs perl6

Initial suggestion by @pchaigno, slightly changed to eliminate false positives such as "classes" or "modules" at the beginning of a line in the =pod

BTW, it would be interesting to just eliminate these areas for language detection.

* Eliminates Rexfile from Perl6

And adds .pod6

* Followup to #2709

I just found I had this sitting here, so I might as well follow
instructions to fix it.

* Adds example for pod6

* Eliminates .pod because it's its own language

* Removes bad directory

* Reverting changes that were already there

* Restored CONTRIBUTING.md from head

I see installation of cmake is advised in README.md

* Eliminates `.pod6`

To leave way for #3366 or succeeding PRs.

* Removed by request, since we're no longer adding this extension

* Sorting by alphabetical order filenames

* Moved from sample to test fixtures

samples/Perl/filenames/Makefile.PL

@@ -0,0 +1,20 @@
+use strict;
+use warnings;
+use ExtUtils::MakeMaker;
+
+WriteMakefile(
+    NAME                => 'Algorithm::Evolutionary::Simple',
+    AUTHOR              => 'JJ Merelo <jj@merelo.net>',
+    VERSION_FROM        => 'lib/Algorithm/Evolutionary/Simple.pm',
+    ABSTRACT_FROM       => 'lib/Algorithm/Evolutionary/Simple.pm',
+    LICENSE => 'gpl',
+    EXE_FILES => [ 'script/simple-EA.pl',  'script/maxones.pl'],
+    PREREQ_PM => {
+        'Test::More' => 0,
+	'Carp' => 0,
+	'Exporter' => 0,
+	'Sort::Key::Top' => 0
+    },
+    dist                => { COMPRESS => 'gzip -9f', SUFFIX => 'gz', },
+    clean               => { FILES => 'Algorithm-Evolutionary-Simple-*' },
+);