Add configuration for vim

- Add ~/.config/vim/vimrc
  + Configure basic stuff
  + Activate spell checks
  + Activate syntax highlighting and ruler
  + Show whitespace characters
  + Add various snippets for mouse handling,
    toggling line numbers, and search
  + Set `vim`-related directories inside
   ~/.config/vim and ~/.local/state/vim
- Integrate extra settings for Python files
  in ~/.config/vim/after/ftplugin/python.vim
  and ~/.config/vim/after/syntax/python.vim
- Add `vim` artifacts in ~/.config/git/ignore

.config/shell/aliases

@@ -3,6 +3,22 @@
 # Aliases used in all kinds of shells
 
 
+# Make this file work standalone in non-interactive `bash` (e.g., ":!cmd" in `vim`)
+
+if [ -n "${BASH_VERSION:-}" ]; then
+    shopt -s expand_aliases
+fi
+
+if ! command -v _command_exists >/dev/null 2>&1; then
+    # This utility is supposed to be defined only in ~/.profile but copied here
+    # to make `$BASH_ENV` work in `vim`, which sources this file only
+    _command_exists() {
+        command -v "$1" 1>/dev/null 2>&1
+    }
+fi
+
+
+
 # Manage the bare `git` repository in ~/ holding the dotfiles
 alias dotfiles='git --git-dir=$DOTFILES_DIR --work-tree=$HOME'
 
@@ -164,3 +180,11 @@ if _command_exists pyenv; then
     alias pyvers='pyenv versions --skip-aliases'
     alias pywhich='pyenv which'
 fi
+
+
+
+
+if _command_exists vim; then
+    alias v=vim
+    _command_exists sudoedit && alias sv=sudoedit
+fi