Feature Request: Add option to keep the latest N episodes of a podcast

[khers]

gonic version: v0.16.2

if from docker, docker tag: sentriz/gonic:latest

I would like to configure (per podcast) the ability to only keep the latest N episodes of that podcast. I don't want to keep an episode I have listened to indefinitely and I don't want to drop it when a user has listened to it (I have several users for this server).