Escape roundtrip

[threefjefff]

Closes [#234]

Stops escaped character sequences being merged back together with other text sequences.
Registers and handles serializtion/deserialization of escape mark type.

Treat the start of inlining a parent block the same way as the begining of a line (to catch sequences where, for example, we've fought with the editor in rich text mode to allow us to insert a # without it turning into a header, thereby serialising to - \#)

PR Checklist

• All new/changed functionality includes unit and (optionally) e2e tests as appropriate
• All new/changed functions have /** ... */ docs
• I've added the bug/enhancement and other labels as appropriate

Environment(s) tested

• Device: [e.g. desktop, iPhone6, etc.]
• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

Additional context

Add any other context about the PR here.

[giamir]

Thanks @threefjefff for the PR.
Overall I think the PR is going in the right direction. 🎉

You should add a unit test for the preserve-escape rule and see if it is worth adding a regression test for the issue Dion reported. Perhaps in the markdown-serializer unit test file.

Great work so far! You can see how much code you ended up writing to fix a relatively simple bug - this is why we should be intentional going forward about what is worth fixing and what is not. More code = more maintenance, more cognitive overhead, more bugs potential, etc...

For this specific bug I think we can go ahead and merge once the PR is in a good state with its relevant tests. Thanks for now. 🙂

[giamir]

would probably use a TagParserRule here for consistency with the rest of the rules we define
parseDOM: [{ tag: "span.escaped" }],

[dancormier]

Thanks for the bug fix @threefjefff. I ran npm run format to resolve some of the formatting inconsistencies and get the lint job passing (8c7a3e0). Other than that, the only things I think necessary to get this merged is what Giamir mentioned.