Switch to regex module for URL identification
Switch to regex module for URL identification

The URL detection regex was failing on input such as 0.1.2.3, as this
input triggered excessive back-tracking in the builtin re module.
The solution was to switch to the regex module, which behaves better.

Closes #913.

explosion/spaCy,oroszgy/spaCy.hu,spacy-io/spaCy,aikramer2/spaCy,honnibal/spaCy,Gregory-Howard/spaCy,aikramer2/spaCy,recognai/spaCy,explosion/spaCy,raphael0202/spaCy,explosion/spaCy,recognai/spaCy,aikramer2/spaCy,Gregory-Howard/spaCy,Gregory-Howard/spaCy,raphael0202/spaCy,aikramer2/spaCy,spacy-io/spaCy,explosion/spaCy,Gregory-Howard/spaCy,honnibal/spaCy,spacy-io/spaCy,honnibal/spaCy,Gregory-Howard/spaCy,raphael0202/spaCy,spacy-io/spaCy,oroszgy/spaCy.hu,oroszgy/spaCy.hu,Gregory-Howard/spaCy,recognai/spaCy,aikramer2/spaCy,recognai/spaCy,oroszgy/spaCy.hu,honnibal/spaCy,raphael0202/spaCy,recognai/spaCy,oroszgy/spaCy.hu,oroszgy/spaCy.hu,spacy-io/spaCy,aikramer2/spaCy,recognai/spaCy,explosion/spaCy,raphael0202/spaCy,explosion/spaCy,spacy-io/spaCy,raphael0202/spaCy