Resolve "Consume links from text file"

Closes #5

See merge request !4

With file:// one can supply a file name which contains a URL per line.
--single-threaded disables parallelizm.

Resolve "Put BROKEN at the end of console report"

Closes #3

See merge request !3

Resolve "Retries"

Closes #2

See merge request !2

Most of all, abstract HTTP Client.
Test reporters.
Test using mock http client.
Test recursive and non-recursive.
Test Axios client separately.