Enhance newline detection to ignore empty inline elements
Add tests for various new line permutations
NodeIterator used in new line check. Test on lists updated. Added blockquote plugin. Removed unused test on tables.
Use TreeWalker instead of NodeIderator. Minor style changes
removed optional arguments in treewalker constructor
Merge pull request #253 from guardian/sh-fix-newline-detection

Relax new line detection