Rewrite to Typescript

[JustinBack]

The crawler is currently written in JS, but I'd like it to be rewritten into typescript for a strict syntax.

[michielbdejong]

Great! While you're at it, maybe also consider if we can switch the annotation GUI of edit.tosdr.org to markdown? See #2.

[JustinBack]

(Tracking on Jira https://tosdr.atlassian.net/browse/TDC-1) TDC-1