[MRG+1] [docs] add note about windows + python3

[MRG] Add FAQ entry on using BeautifulSoup in spider callbacks

Typo fixes

[MRG+1] Fix issue HttpCompressionMiddleware tries to decode HEAD responses #1899

[MRG+1] Added: Retrying scrapy.core.downloader.handlers.http11.TunnelError

[MRG+1] Use "url" variable in the example

Instead of hardcoded http://www.example.com: without it url variable is unused and only one request will make it past dupefilter.

DOC Add info and example on errbacks

[DOC][Overview] Use idiomatic .extract_first()

[MRG+1] Prevent empty warnings in case of certificate verification failures

Merge 1.0.6 release notes

Fixes #1976

Github >> GitHub

Bump w3lib version dependency in setup.py

[MRG+1] Fix canonicalize_url() on Python 3 and re-enable tests