Bug 7963 Parallel HTTP requests when checking URLs

Bug 7963 Parallel HTTP requests when checking URLs

Current script check-url.pl checks URL found in 856$u by sending HTTP
requests, one by one. The next request can't be sent before the previous
one get a result, which can be very slow for dead URL. I propose a new
script which send multiple requests simultaneously which improve
drastically URL checking execution time.

This script is based on AnyEvent and AnyEvent::HTTP CPAN modules.
Add new dependencies AnyEvent & AnyEvent::HTTP.

See doc: perldoc check-url-quick.pl

Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>