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/env

@@ -26,6 +26,13 @@ export DOTFILES_DIR="$XDG_DATA_HOME/dotfiles"  # also set in ~/.local/bin/dotfil
 [ -t 0 ] && export GPG_TTY=$(tty)
 
 
+if _command_exists vim; then
+    export EDITOR=vim
+    export SUDO_EDITOR="$EDITOR"
+    export VISUAL="$EDITOR"
+fi
+
+
 export PAGER=less
 export LESS="--chop-long-lines --ignore-case --LONG-PROMPT --no-init --raw-control-chars --status-column --quit-if-one-screen"
 
@@ -47,9 +54,11 @@ unset _bat
 # Move common tools' config and cache files into XDG directories
 
 export BAT_CONFIG_PATH="$XDG_CONFIG_HOME/bat/config"
+export INPUTRC="$XDG_CONFIG_HOME/readline/inputrc"
 export LESSHISTFILE="$XDG_STATE_HOME/less/history"
 export PSQLRC="$XDG_CONFIG_HOME/psql/psqlrc"
 export PYENV_ROOT="$XDG_DATA_HOME/pyenv"
 export PYTHONPYCACHEPREFIX="$XDG_CACHE_HOME/python"
 export PYTHONSTARTUP="$XDG_CONFIG_HOME/python/startup.py"
 export PYTHON_HISTORY="$XDG_STATE_HOME/python/history"
+export VIMINIT='let $MYVIMRC="'"$XDG_CONFIG_HOME"'/vim/vimrc" | source $MYVIMRC'