Adds a "do what I mean" multiple-cursor selection with the logic that
I find most useful:
* If there is no active region, mark the next line (or lines, based on
prefix argument)
* If there is an active region that spans multiple lines, call
`mc/edit-lines`
* If there is an active region on a single line, trigger a custom
selection hydra with functionality equivalent to
`mc/mark-more-like-this-extended` but a slightly improved user
experience
Hopefully this will make it easier to get into the habit of actually
using multiple-cursors without calling the mc commands via M-x
Configures Emacs' `customize` to write directly to my Emacs
configuration. This comes with the caveat that the new config will
only be loaded if my Emacs is rebuilt.
Builds an Emacs that is not only configured with the required packages
but with the entire Emacs configuration for my personal setup.
This means that `nix-env -iA tools.emacs` will install a
fully-configured Emacs that can be launched as the window manager from
my ~/.xsession.