Better default keybinding for Remove Word Right

So the default for `Remove Word Left` was `Ctrl-Backspace`, which makes a lot of sense: `Backspace`, `Left`, and `Right` keys all operate one letter at a time, and `Ctrl` makes them operate one word at a time. But the default for `Remove Word Right` was `Alt+D`, which didn't make any sense to me, because it seemed highly inconsistent, and also my window manager (Ubuntu Unity) gets confused by the alt key from time to time. 

So, I propose that `Ctrl-Delete` is a much better shortcut, because it makes the `Ctrl` key consistently delete forward by words just like it makes the `Backspace` key delete backwards by words.

If you disagree, I guess I'll just keep this to my personal config, but I felt strongly about this consistency so I wanted to share ;-)
Keep Alt-D for macs.
Merge pull request #112 from robru/patch-1

Better default keybinding for Remove Word Right