AHLRAP-1467 Fix IPython console completion pop-up on all characters

The completion calculator caches the characters which trigger a
completion ('.', or [a-zA-Z]) based on the user preference, and whether
there is more than one completion processor registered.

The console calls the API with 0, as the number of completion
processors. The editor calls it with the number of processors specified.
 The result is inconsistent caching depending on which is called first.

This makes the cache behave consistently for the specified preference.
It's possible that there are SimpleAssistProcessors that would no longer
be invoked for every character, but, AFAICS this would only affects the
template processor, and that seems to work correctly after this change.

Change-Id: Ie6ab792fbef093b9396ef84b9d7a6a07b8edecc5
Merge pull request #106 from ahlmss/fix_console_completion_popup_on_all_keystrokes

AHLRAP-1467 Fix IPython console completion pop-up on all characters