Specification of HTML version and/or supported HTML tags in MLS

[christiankral]

The Modelica Language Specification shall state

• what HTML standard a Modelica tool has to support (proposal HTML5) and/or
• what subset of HTML5 tags shall be supported.

This issue is triggered by modelica/ModelicaStandardLibrary#2519 (comment), which requires to support <figure> and <figcaption>.

[christiankral]

@beutlich I think it makes sense to assign someone to this ticket. Could you possibly do that as I do not have the permission to set the assignee.

[beutlich]

Here's a test class to test some HTML features in different Modelica environments.