- [ ] Convert to Typed Racket
  - requires: build executable (otherwise too slow)
- [x] Build executable
  Implies fix of "collection not found" when executing the built executable
    outside the source directory:

    collection-path: collection not found
      collection: "tt"
      in collection directories:
      context...:
       /usr/share/racket/collects/racket/private/collect.rkt:11:53: fail
       /usr/share/racket/collects/setup/getinfo.rkt:17:0: get-info
       /usr/share/racket/collects/racket/contract/private/arrow-val-first.rkt:555:3
       /usr/share/racket/collects/racket/cmdline.rkt:191:51
       '|#%mzc:p

- [ ] Support redirects
  - should permanent redirects update the feed somehow?
- [ ] Support time ranges (i.e. reading the timeline between given time points)
- [x] Implement rfc3339->epoch
- [x] Remove dependency on rfc3339-old
- [x] remove dependency on http-client
- [ ] optional text wrap
- [ ] write
- [x] caching (use cache by default, unless explicitly asked for update)
  - [x] value --> cache
  - [x] value <-- cache
    requires: d command
- [ ] timeline limits
- [ ] feed set operations (perhaps better done externally?)
- [ ] timeline as a result of a query (feed set op + filter expressions)
- [ ] named timelines
- [ ] config files
- [ ] parse "following" from feed
  - following = <nick> <uri>
- [ ] parse mentions:
  - @<source.nick source.url> | @<source.url>
- [ ] highlight mentions
- [ ] filter on mentions
- [ ] highlight hashtags
- [ ] filter on hashtags
- [ ] hashtags as channels? initial hashtag special?
- [ ] query language
- [ ] console logger colors by level ('error)
- [ ] file logger ('debug)
- [-] commands:
  - [x] r | read
    - see timeline ops above
  - [ ] w | write
    - arg or stdin
    - nick expand to URI
  - [ ] q | query
    - see timeline ops above
    - see hashtag and channels above
  - [x] d | download
  - [x] u | upload
    - calls user-configured command to upload user's own feed file to their server
  Looks like a better CLI parser than "racket/cmdline": https://docs.racket-lang.org/natural-cli/
  But it is no longer necessary now that I've figured out how to chain (command-line ..) calls.
- [ ] Suport immutable timelines
    - store individual messages (possibly in something like DBM or SQLite)