Collected updates:
* Always use example.com as domain in tests
* disabled invalid-char test, the invalid char seems to have gone missing
* Add test for External links: wiki links within external link (Bug 3695)
* extended test for Bug 2702: Mismatched <i>, <b> and <a> tags are invalid
* there should be no more empty <i> and <b> tags in the output
* Link to image page- image page normally doesn't exists, hence edit link
* update all section edit texts to use new link title format
* update fixed tests for invalid html in title/alt attributes (Bug 1887), add
extra tests for this
* Fix typo in Cat link
* add test for fixed Bug 2095: link with pipe and three closing brackets
* update test for html id validation