Fixed #69. url_sanitize no longer crashes on unparsable urls.
Fixed #69. url_sanitize no longer crashes on unparsable urls.

Also optimized the code to bypass parsing when not in safe_mode and return
immediately upon failure rather than continue parsing when in safe_mode.

Note that in Python2.7+ more urls may fail than in older versions because
IPv6 support was added to urlparse and it apparently mistakenly identifies some
urls as IPv6 when they are not. Seeing this only applies to safe_mode now,
I don't really care.

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