Refactor neovim config (#2)

Changes include:

- [x] Use init.lua instead of init.vim
   - Some keybindings are still to be converted
- [x] Use packer as a package manager instead of vim-plug
- [ ] Use built-in lsp instead of coc.nvim
   - [x] Set up language servers
   - [x] Completion
   - [x] Formatting (previously coc-prettier, now neoformat)
   - [ ] Snippets
- [ ] Replace fzf with telescope.nvim
- [x] Implement treesitter syntax highlighting
   - More info: https://github.com/nvim-treesitter/nvim-treesitter

Note that this requires neovim nightly until 0.5 is released

Reviewed-on: #2
Co-authored-by: Marko Korhonen <marko@korhonen.cc>
Co-committed-by: Marko Korhonen <marko@korhonen.cc>

home/.config/nvim/lua/settings.lua

@@ -0,0 +1,61 @@
+local o = vim.o
+local g = vim.g
+local cmd = vim.cmd
+
+------ Appearance ------
+
+-- Set colorscheme
+require('onedark').setup()
+
+-- True colors
+o.termguicolors = true
+
+-- Floating window transparency
+o.winblend = 10
+
+-- Remove extra line
+o.cmdheight = 1
+
+-- Always show signcolumn
+o.signcolumn = 'yes'
+
+-- Blinking cursor
+cmd 'set guicursor=i:ver1'
+cmd 'set guicursor+=a:blinkon1'
+
+-- Gutter and cursoline bg transparent
+cmd 'highlight CursorLineNr guibg=transparent'
+cmd 'highlight SignColumn guibg=transparent'
+
+------ Misc -------
+
+-- Use suda by default
+g.suda_smart_edit = 1
+
+
+-- Split direction
+o.splitbelow = true
+o.splitright = true
+
+
+-- Case insensitive search
+o.ignorecase = true
+o.smartcase = true
+
+-- Use mouse
+o.mouse = 'a'
+
+-- Use system clipboard
+o.clipboard = 'unnamedplus'
+
+-- Autoindent and syntax higlight
+o.autoindent = true
+o.smartindent = true
+o.tabstop = 4
+o.shiftwidth = 4
+cmd 'syntax on'
+cmd 'filetype on'
+cmd 'filetype plugin indent on'
+
+-- Disable auto commenting
+o.formatoptions = 'cro'