keybinder: new package

keybinder is a library for registering global keyboard shortcuts.
keybinder works with GTK-based applications using the X Window System.

https://github.com/engla/keybinder/
gnome-terminator: add missing dependencies (for extra features)

Add 'keybinder' and 'python-notify' as dependencies. Fixes this:

  $ terminator
  [...]
  Warning: python-keybinder is not installed. This means the hide_window shortcut will be unavailable
  [...]
  ActivityWatch plugin unavailable: please install python-notify
Rename 'gnome-terminator' to 'terminator'

Align the package name with what other distros call it.

Other distros: Fedora, Debian, Archlinux, OpenSUSE, Mageia, Slackware
(and probably more).