title html tag is mangled if title contains any of <>_

See https://isocpp.org/files/papers/D2529R0.html.

In paper.md: `title: generator<T> should have T&& reference_type`

In html file: ``<title>generator`&lt;T&gt;`{=html} should have T&amp;&amp; reference\_type</title>``

Title as shown in browser: ``generator`<T>`{=html} should have T&& reference\_type``