Ignore None's values when using the ItemLoader.
Unused re import and PEP8 minor edits.
Expose current crawler in the scrapy shell.
PEP8 minor edits.
Updated shell docs with the crawler reference and fixed the actual shell output.

Also updated the shell example with a reproducible code example.
Updated the tutorial crawl output with latest output.
RegexLinkExtractor: encode URL unicode value when creating Links
replace unencodeable codepoints with html entities. fixes #562 and #285
Fix tests for Travis-CI build
BaseSgmlLinkExtractor: Fixed unknown_endtag() so that it only set current_link=None when the end tag match the opening tag
BaseSgmlLinkExtractor: Added unit test of a link with an inner tag
BaseSgmlLinkExtractor: Fixed the missing space when the link has an inner tag
Fix HtmlParserLinkExtractor and tests after #485 merge
Docs: 4-space indent for final spider example
Fix wrong checks on subclassing of deprecated classes. closes #581