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

.config/git/ignore

@@ -1,3 +1,6 @@
+# pyenv
+.python-version
+
 # Vim
 # Source: https://github.com/github/gitignore/blob/main/Global/Vim.gitignore
 #