Support 256 Color

[mikeslattery]

Describe the feature you'd like

Support for 256 color like the vim plugin

Describe risks you've considered

I can't think of any technical risks. It's possible some users could settle for 256 color config, if they can't easily figure out how to get true color working.

Describe alternatives you've considered

My issue is that Mosh doesn't support true color. I discovered a patch which should work for me, but it appears to not work correctly in some uses cases.