nvim: restructure config files

nvim/lua/config/mappings.lua

@@ -0,0 +1,21 @@
+local map = vim.keymap.set
+local cmd = vim.cmd
+
+vim.g.mapleader = " "
+
+-- Undo/Redo in insert mode
+map("i", "<C-z>", cmd.undo)
+map("i", "<C-y>", cmd.redo)
+
+-- Ctrl+s saves the current buffer in normal/insert mode.
+map("n", "<C-s>", cmd.w)
+map("i", "<C-s>", cmd.w)
+
+-- Move Text
+map("n", "<S-a>", ":m+1<CR>")
+map("n", "<S-d>", ":m-2<CR>")
+
+-- Indent
+
+-- Make Shift-Tab undo indent.
+map("i", "<S-Tab>", "<C-d>")