The Ctrl, Alt and Shift bits in Controller/button activate with either
left or right modifier keys, and either can be used to take screenshots
/ zoom / show debugging info rather than left modifiers only.
Delete now sets Controller/key to 0x7f rather than being ignored (by
setting Controller/key to 0x00).
Ctrl + letter now sets Controller/key to 0x01-0x1e rather than being
ignored: for example, Ctrl+S will set Controller/key to 0x13.
Controller/vector is no longer called twice per key press (the extra
call with Controller/key set to 0x00 is removed).