Emacs: Advise C-w and M-w to work without region.

If there is no region, they will kill or copy the present line.
Emacs: Add unfill-paragraph function.

Note that bind-key comes with use-package, so I can convert my other
bindings to use it.
Emacs: Use use-package's macro, bind-key.

bind-key is a helper macro that comes with use-package. Not only is it
less verbose, but it also allows me to use its
"describe-personal-keybindings" function.

Note that this commit shouldn't work yet, as use-package is required
later than bind-key is used.
Emacs: Move packages section to the beginning.

This allows me to make use of bind-key from the beginning.

Also, docs updates.
Emacs: Move "lines" section into keyboard section.
Emacs: Promote headline in "Packages."

This should make navigating my config easier. Made possible by moving
the packages set-up to the first section.
Emacs: Clean up 'Settings' section.
Emacs: Promote 'Functions,' fire 'Macros.'

I'm not using any macros across sessions at the moment, and if I do,
they can have their own headline.