[FEATURE] Mouse support

[Hoekstraa]

This is a purely comfort related feature.

If this application were to support the mouse (like vim, tmux, etc.) you could be able to:

1. click on items in the feed list
2. click on items in the posts list
3. scroll through aforementioned lists
4. scroll through opened posts
5. possibly? click on hyperlinks in posts

The last one of course would require for a similar feature to exist for keyboard-only users. There may be more ease-of-use opportunities in the future of neix.

Since ncurses has the ability to detect mouse usage, there would be no need for any change in library usage, only programmers' time.

[qw3rtty]

@JanSHoekstra Thanks for opening this issue. I will take a look into it