Add a 256-color theme?

[danielshahaf]

Shall we add a 256-color theme? We could enable it automatically after checking the terminal's capabilities in ${terminfo}.

[phy1729]

Since themes will be sourced or called, the main theme could support both. It may be a good idea for z-sy-h to provide a _supports_256_color callable so each theme doesn't have to roll its own.

[tmpm697]

Would it cost load time/cpu intense if we use more colors? If yes please give user a choice.

I tested with fast-sytanx-highlight and its throughput still slower than this plugin but I'm not sure if it comes from colors or code.

[danielshahaf]

I don't foresee any performance issues here.