Allow for converting of Symbols to HTML code

[clapierre]

It would be good if we can have the following

® convert to  ®
© convert to ©
™ convert to ™
° convert to °

I am sure there are others but was surprised that Tidy didn't automatically support this or had a configuration switch to allow for this conversion.
Thanks.

[clapierre]

Looks like you convert & to &
So why not the others?

[geoffmcl]

@clapierre thank you for the issue...

I presume you have explored the --preserve-entities yes option... where tidy will maintain the named entities found in the source...

Otherwise it will store the utf-8 conversion in its lexer text buffer, and the fact that it was a named entity in the source is lost forever...

Now what you are suggesting is an option like say --output-named-entities yes, or something like that, where all utf-8 output that matches a known named entity, is output as the name instead... hmmm, possible I suppose...

At present it would mean passing every output code point through a table of some 2032 known entities, severely impacting the output processing... but I suppose some optimization, hashing, ... could be done... but even so... not yet sure it is worth it...

But why would you want that? That is, what is the real use case for such an option? Other than simply it would be good!

I think the outputting of & as & is sort of a separate issue, but would also need to be taken into account...

Look forward to further feedback, comments, code, patches, PR,... to demonstrate the viability of the idea... and the need... thanks...