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
Merge pull request #485 from bblanchon/sgml-extractor-link-text

SgmlLinkExtractor: Fixed link text when there is an inner tag