feature request: zsh support

[ajeetdsouza]

If users have custom prompts, etc. configured on zsh, they'd be able to use that configuration with tuterm. While lack of zsh support is not a dealbreaker, it's definitely a nice-to-have.

[veracioux]

This is a long planned feature. But instead of providing specific cases for each shell, I proposed a more general approach in #3. I'll try to implement it as soon as I can because it opens up a lot of new horizons, but I have been very busy with other stuff lately.