As realized in #796, Latin-1 characters are supported as input but render in the wrong font.

One approach is to allow single-character macros (like TeX active characters) and macro é to \acute{e}.
Here's an experiment in this direction. This works, but we unfortunately need different macros for text and math mode. Effectively we need \ifmmode support. This can't be done in the macro expander, but could be done in the parser... Alternatively, we could add support for \acute in text mode, even though LaTeX doesn't allow that.

Of course, actual text-mode support in this way would require first resolving #638 (text-mode accent commands)