Make dotfiles compatible with gitpod style dotfiles

Add an install.sh that attempts to determine the OS, install stow and
then call my apply-dotfiles script to use stow.

The old installation process that was based on nix, has been moved to
nix-install.

apply-dotfiles

@@ -1,13 +1,26 @@
-#!/usr/bin/env nix-shell
-#! nix-shell -p stow -i bash
+#!/usr/bin/env bash
 
-stow bash
-stow sh
-stow readline
+apply_dotfile() {
+  directory_to_stow="${1}"
+  stow --adopt -S -t "${HOME}" "${directory_to_stow}"
+}
 
-stow vim
+# Adopt will change the files in stow to match existing files.
+# We don't want this, we just want to handle existing files gracefully.
+# We simply adopt all the files and then at the end restore our git repo to undo changes
+restore_from_adoption() {
+  git restore .
+}
 
-stow ruby
-stow python
+apply_dotfile bash
+apply_dotfile sh
+apply_dotfile readline
 
-stow ssh
+apply_dotfile vim
+
+apply_dotfile ruby
+apply_dotfile python
+
+apply_dotfile ssh
+
+restore_from_adoption