chore(dotfiles): freshen kitty.conf
chore(dotfiles): freshen kitty.conf

1. Move kitty.conf out the way.
2. Select "Preferences..." from the kitty application menu; this creates
   a new kitty.conf.
3. Look at the diff, bringing old customizations back across.

The main differences since last time are:

- kitty now shows default settings as comments. This is nice, because it
  means at a glance you can see what you've actually overridden.
- Some descriptions are longer now.
- Some new options.
- I chose not to carry across the `macos_thicken_font` override; I don't
  really mind the look without it.
- Some features removed; eg. `open_url_modifiers`; as changelog states:

  > Backward incompatibility: The options to control which modifiers
  > keys to press for various mouse actions have been removed, if you used
  > these options, you will need to replace them with configuration using
  > the new :ref:`mouse actions framework <conf-kitty-mouse.mousemap>` as
  > they will be ignored. The options were: terminal_select_modifiers,
  > rectangle_select_modifiers and open_url_modifiers.

  So I'll make that adjustment in the next commit.

wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent