Multi-line formatting is occassionally broken

[martinheidegger]

In some cases multi line formatting seems to be breaking the lines wrongly.

echo "\nThese are the fancy **parts of the world and you will never** know what is going on. _Or are you thinking of things_. \`here are the monsters of the other side\`" | bin/msee --width=25

output:

Multi-line breaks are implemented in varsize-string which makes this likely an issue for visual-width