[Ur] HTML5 support (was: Re: PATCH: <progress> tag)

[Adam Chlipala]

austin seipp wrote:
> I was going to strike a compromise and ask if it would be allowable to
> reject any HTML5 elements by default unless a '-html5' flag was passed
> or something, since that seems much more sound, but beyond elements
> there are a few new attribute definitions as well as deprecations etc.
>    

That sounds nasty, but it could easily be supported by splitting some 
HTML stuff into separate .urs files that are used based on command-line 
flags or project settings.

I'd like to wait for other opinions to be expressed here.