[Feature] Status line parts as modified and overwrite mode indicator’s

[Bellavene]

[Andriamanitra]

I think it would be great to be allow users to specify colors in the statuslinel/statusliner. Then you could write a simple plugin to implement this, or any other way to signal state through font color. In practice this could mean that the users specify the colors directly as ANSI escape codes, or possibly through a new function available at statusline (for example "$(color:#ff00ff)" to use hex color codes and "$(color:default)" to read color by name from the colorscheme). As far as I understand something like this is currently impossible to do in a plugin due to how (s *StatusLine) Display() is implemented.

I don't like flickering colors as the default behavior though. I think it would be ugly and confusing.

[Bellavene]

On the other side, you don't waste space with additional symbols popping around, and you clearly see modes changing by color.
I believe the line & col numbers in status line is even better for overwrite modes indication. Would be glad to use it, true minimalism.