Support arbitrary start numbers for ordered lists in remarkup

Summary: Fixes T6377.

Test Plan: Unit tests, mostly. Also checked a local install to see if this felt sensible.

Reviewers: Thirtyate, epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: Korvin, epriestley

Maniphest Tasks: T6377

Differential Revision: https://secure.phabricator.com/D10742
Remove history support for console prompts on Windows

Summary: Fixes T6348.

Test Plan: Run `arc diff --nolint --nounit` and see the expected prompt, instead of just one word.

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T6348

Differential Revision: https://secure.phabricator.com/D10743