README: add link to EuroPython presentation, sequence install list, other tweaks
README: post-render tweaks
README: one more post-render tweak (to nested numbered list)
README: rollback nested-numbered-list tweak (which alas did not improve GFM), clarify whose packages (emacs, not python, OS, or other)
Merge pull request #1 from TomRoche/master

improved README