Configure Python develop tool chain

- use pyenv to manage the develop environments
  + install several Python versions (3.7 - 3.10 and 2.7)
  + each version receives its own copies of black, pipenv, and poetry
- add two more virtual environments based off the latest version:
  + "interactive" => default environment optimized for interactive
                     usage with with black, bpython, and ipython
                     (also receives accidental `pip install`s)
  + "utils" => hosts various globally available tools/apps
               (e.g., mackup and youtube-dl)
- add installation and update scripts for the entire tool chain
- set up completions for bash and zsh
- set up convenient aliases
- configure bpython
- configure poetry

.profile

@@ -11,6 +11,10 @@ export REPOS="$HOME/repos"
 
 export LESSHISTFILE="$HOME/.lesshst"
 
+export PYENV_ROOT="$HOME/.pyenv"
+# No need for *.pyc files on a dev machine
+export PYTHONDONTWRITEBYTECODE=1
+
 export PSQLRC="$HOME/.psqlrc"
 
 
@@ -26,6 +30,7 @@ prepend-to-path () {  # if not already there
 
 prepend-to-path "$HOME/bin"
 prepend-to-path "$HOME/.local/bin"
+prepend-to-path "$PYENV_ROOT/bin"