Feature request: override highlight groups

[leoluz]

First of all, congrats for your theme. It looks really nice with cool treesitter support.

There are a few things I'd like to customize to my taste (eg. Telescope border colors).
It would be awesome if we could customize highlight groups in the setup function. Something like what onedarkpro does:
https://github.com/olimorris/onedarkpro.nvim#configuring-highlight-groups

[leoluz]

This is how I achieved the customization I wanted:

local colors = require('onedark.colors')
vim.cmd("highlight TelescopeBorder guifg="..colors.grey)
vim.cmd("highlight TelescopePromptBorder guifg="..colors.grey)
vim.cmd("highlight TelescopeResultsBorder guifg="..colors.grey)
vim.cmd("highlight TelescopePreviewBorder guifg="..colors.grey)

Its not too bad but having the support to do it directly in the setup() function would be better.

[xeluxee]

#42 is merged: now you can use highlights section in setup option
Sample code:

require('onedark').setup {
  colors = {
    bright_orange = "#ff8800",    -- define a new color
    green = '#00ffaa',            -- redefine an existing color
  },
  highlights = {
    TSKeyword = {fg = '$green'},
    TSString = {fg = '$bright_orange', bg = '#00ff00', fmt = 'bold'},
    TSFunction = {fg = '#0000ff', sp = '$cyan', fmt = 'underline,italic'},
  }
}