A very me-specific task grepper for vimwiki.

Inspired by a bit of fediverse discussion today that mentioned the
preview pane.

Saves some keystrokes on importing to wiki.

Uses git-diff-index.

Also adds `git ec` alias so maybe I remember to use this.

Based on phasemoji.  Fails if no php.

Async here is great.

I was messing with this at... Some point in the last few years.

This just wraps the older calendar(1) invocation for the moment, just
adding a layer of indirection so it can include other data.