Fix cursor foreground color

[rkfg]

The new gocui black color is gray unless dimmed. It's better to dim it for readability.

[edouardparis]

Thanks !

[hieblmi]

Thanks for the PR @rkfg. For some reason the contrast still isn't right for me.

Is there a config flag I have to set?

[rkfg]

That's weird. No, there's no config flag, it should set the foreground color to pure black. What's your normal background color there in other rows?