[kikpukyi] Digraphs expected

Fancy keyboards, especially virtual keyboards, have the ability to send multiple sequential key presses to the application, for example digraphs and polygraphs.  However, such digraphs are only useful in certain modes, most commonly typing text, and may be actively harmful in other modes, e.g., a keystroke driven command mode like for vi.  For example, often we want to provide the feature of undoing the last keystroke.  Thus, an application needs to communicate with the keyboard what features it should provide at the moment.  This seems messy.  Alternatively, the user can put the keyboard in various modes manually, but that requires more keystrokes.