Bug fix in paragraph wrapper when block tags are encountered.

- Block tokens weren't closing open p-tags in all cases. This led
  to wt2wt failure on this testcase (simplified and extracted from
  en:St. Louis County Road 91): "<div />\n\n\n<div />a\n\nb".

- One more html2html test green. No changes in any other tests and
  my version of selser tests.

- Fixes RTing of the above wiki page.

Change-Id: I6112cf829f038a2c37f56ef2bc39927cb1cae2bb