Remove confluence-mode

I no longer have reason to use Confluence (Atlassian's Wiki product).
Sane trackpad scrolling on OS X
Bring back flat imenu index in python-mode

This populates the imenu index with "classname.membername" entries,
instead of a single "classname" entry that you have to select to
get the list of members. I use ido-ubiquitous-mode so I can find all
matches by typing just "membername" without having to remember the
classname.
Turn off markdown-mode's annoying auto-indentation
Enable upcase-region (C-x C-u)

I actually do use it from time to time.
magit: Use hl-line-mode's color for current selection
Install dockerfile-mode and rust-mode
do-after-save: Slight improvement to docstring
Enable narrow-to-region (C-x n n)

I actually do use it from time to time.