Filter from original rows, not current

[lukebooth]

What this does

Added option to filter from the original list of rows rather than what is currently being displayed

My reasoning

Just plugging this library into my app, I noticed the filter would only filter the rows that were displayed on screen, not the original set of rows loaded. I needed the ability to use backspace to start the filter over instead of hitting a reset button. If what I described is how this library actually works, then I may have been running into a bug and you can just close this PR.

Example

With this list:

-- Luke
-- Jim
-- John
-- Johnny

Filtering to Jo would only show John and Johnny, but backspacing to just J wouldn't bring Jim back to the list.