CRM-14367 check for valid html structure - regex function to come
CRM-14367 add regex to check for applicability of table cell
CRM-14367 code tidy ups
CRM-14367 remove unused  & try catch in favour of hard fail (can't think of any cases where soft fail is good
Merge pull request #3147 from eileenmcnaughton/CRM-14367

CRM-14367 check for appropriateness of <td> separator