Support for ZenUML diagrams

[jwatt]

Could configuration to enable the newer ZenUML support be added?

According to the Integrating with your library/website section of https://mermaid.js.org/syntax/zenuml.html it involves something like this:

<script type="module">
  import mermaid from 'https://cdn.jsdelivr.net/npm/mermaid@10/dist/mermaid.esm.min.mjs';
  import zenuml from 'https://cdn.jsdelivr.net/npm/@mermaid-js/mermaid-zenuml@0.1.0/dist/mermaid-zenuml.esm.min.mjs';
  await mermaid.registerExternalDiagrams([zenuml]);
</script>

[jwatt]

(Similar request to #98.)

[timkpaine]

Yes I think this would be quite easy to do. I will see about a refactor as the inline JS has gotten a little complicated, but now that we got 1.0 out perhaps we can do a bit of a cleanup for 1.1

[jwatt]

That sounds great. Thank you for the very prompt reply.