Fix SourceAnnotation ranges and refactor to std::fmt::Display

[zzau13]

In test_i26 what should be the output?
panic or anything other than the label disappearing?

I would panic or even refactor to TryFrom. What you prefer

Fix #26

[zbraniecki]

This PR looks awesome! Thank you so much!

for test_i26 I'd panic for now. We can improve fallibility later.

[zzau13]

Ok, should panic

[zbraniecki]

Can you mark this PR as draft until you're ready for review? I'm excited to review it :)

[zzau13]

It seems that the coverage is not correct.
Exactly tests/fixtures/no-color/multiline_annotation.yaml.

In the report details:

thread 'test_fixtures' panicked at 'SourceAnnotation range `(23, 786)` is bigger than source length `766`', src/display_list/from_snippet.rs:190:9

So I think there are more bugs. So I will review that part of the logic.

[zzau13]

Should already be presentable and debb3e2 doubles performance

[zbraniecki]

Overall - very impressive! Thank you! The patch looks great and is definitely a significant clean up!

Several leftovers:

• the format example crashes, fix the second annotation to (21,724) (I assume the new values are a fix to calculations)
• same with the bench
• your branch seem to have broken color mode - cargo run --example format --features color.

[zzau13]

The changes are already there.

A detail is that the ranges are start at 0, it should start at 1.
We would have to put much more coverage.

Well but for this PR there is already enough,

[zbraniecki]

Thank you! This looks awesome!