Feature Request: color themes

First of all thanks for this project.  I think it's awesome.

I think my terminal is pretty, but when I share it, the colors don't translate--so it can be awkward for the recipient.  I like how asciinema handles this--with an http parameter (https://asciinema.org/docs/embedding).  It would be like:

https://shellshare.net/r/Zwhd1LIzaj1KLrAZR3?theme=solarized-dark

Thanks for considering it!
