HOTFIX: GUI controller crashes on first run

The code to build inputMethodList read config file directly and failed
on missing keys.
HOTFIX: Should check Unity on every key press

There is just no other way, even though this is very inefficient. We
can't reliably check it at engine startup (IBus now uses single global
engine by default) and both the reset and disable signals aren't fired
when Dash is enabled. But the short-circuit nature of python's logical
"and" operator ensures is_in_unity_dash() is not called on other
environments.
HOTFIX: Controller.py still crashes