Reach >=90% code coverage with tests

[rkrisztian]

Let's say, this is a first milestone to fix test coverage to an extent that makes me more confident the app works as expected.

I am not sure yet about aiming for 100% coverage, I would balance it against practicality, for whatever reasons I will find.

(Of course I could have added the tests much sooner, but the first version of the app was created as a single Perl script file with absolutely no tests, so I am only doing damage control here.)

[rkrisztian]

So far done:

• A few percent with LineCollector, ConsoleResultsPrinter tests.
• +10% with HtmlResultsPrinter tests.
• +6% with FileFInder tests.
• +1% with the search.conf package.