Prefer `{Date,Time}.current` over `.today`/`.now`

`Date.current` and `Time.current` take `Time.zone` and
`config.time_zone` into account, falling back to `Date.today` and
`Time.now` respectively if a zone isn't set.
I'm open to other ideas. It's just the most convenient setup I've found to writing prose in vim so far.

```
:set fo?
formatoptions=jcqltwn
```