Feature request: Stop htmlchar strip to allow validation of formatting

[marcusgreen]

#Thanks to Dave Foord for this idea which has been something in the back of my mind for a long time. There are situations where it would be useful to not only evaluate plain text but also the formatting around it. For example

• chemistry (where formula have numbers in subscript)
• Correct referencing when creating a bibliography
• Law – with the various legal protocols of how information is displayed

I have no timetable on this, but I think it is desirable.