Tweaks to make it easier to work with big buffers/slow matchers

This PR has two sections.

The first is to allow C-l to re-run a query (and thus refresh the screen). This is useful if for whatever reason the matcher was stopped in the middle and your filter results are not complete.

The seconds creates a new request type to refresh the prompt alone. Previously you needed to wait for the filtering to finish before you see the prompt updated, but this change redraws the prompt alone first, and then proceeds to re-run the query.