We don't yet have any code to render them, and the vte parser seems
to truncate incoming image sequences ~1kb in size, so more work is
needed to make this useful.
This enables selecting an italic font when the cell is italic,
but has more power beyond just that simple property.
This runs a little hot on the CPU so there's probably some caching and
tweaking that can be done to make the evaluation a bit cheaper.
This eliminates the zsh reversed % artifact issue.
Added a feature flag to turn on diagnostics even in release mode;
`cargo run --release --features debug-escape-sequences`
