Factor out date period
Add time period
Parse natural language such as after 3 hours or 5 minutes earlier
More flexibility in parsing datetime
More false positive checks for typo
Remove the datetime that was matched
Parse range of IDs when completing and deleting
Return null if empty
Revert "Update ParserTest"

This reverts commit 831425906c371fddd291268a2b0ced70c6ee0f85.
Parse "ago"
Order matters