* fix: Upgrade markdown-it to fix text collapse bug
* tsc. Need to overwrite the types for now until all Prosemirror modules are updated, they have recently been converted to Typescript and the types conflict
This PR moves the entire project to Typescript. Due to the ~1000 ignores this will lead to a messy codebase for a while, but the churn is worth it – all of those ignore comments are places that were never type-safe previously.
closes#1282
