Allow nested symlinks

[sporkd]

This allows you to create symlinks not just in the top level $HOME directory, but also inside nested directories so you can track files like $HOME/.ssh/config. You use + signs to signify additional directory delimiters on files with the .symlink extension. A great example is instead of symlinking the entire ~/.config directory into source control, you can now just track the nested ~/.config/nvim directory.

Examples: .dotfiles/ssh+config.symlink -> ~/.ssh/config .dotfiles/ssh/ssh+config.symlink -> ~/.ssh/config .dotfiles/vim/config+nvim.symlink -> ~/.config/nvim .dotfiles/vim/config+nvim+init.vim.symlink -> ~/.config/nvim/init.vim

• Backwards compatible with how it currently works.
• Creates nested parent directories if they don't exist.
• Symlinks both directories and files.