Log Message:
khal: update to 0.11.2.

0.11.2
======

* FIX khal `at` also uses `event_format` not `agenda_event_format`
* FIX duplicating an event using `p` in ikhal
* NEW Add ability to change the minimum number of months displayed with
  `min_calendar_display`
* FIX ikhal don't crash when jumping long distances in time
* FIX do not use urwid's private methods, would crash with latest urwid version
* FIX light colorscheme in ikhal, would crash with recent urwid versions
* FIX better error messages when we cannot import an event