Request: add configurable option for how many posts to pull at a time or an option to load more

[SleepyCatten]

Current functionality:
Substitoot pulls in non-local replies to posts and loads up to 20 of the actual last posts on a person's profile from a non-local server.

The issue:
You cannot configure the option, so you'd still need to manually browse their profile (which might be private) on their server.

Suggestions:

1. Add an option to configure how many posts to pull (with something to make sure you don't overload another server).
2. Load 20 at a time, but have a button at the bottom to load more after each load is done. (Toggleable.)
3. Load 20 at a time, but scrolling down their profile page further will load more posts as you reach the bottom. (Toggleable.)