Fixes#3518.
Changes in Keyman Configuration will now apply immediately. This removes
the OK and Cancel buttons from the dialog and means that all actions
are consistent in when they are applied, unlike previously. This also
matches the Windows 10 Settings metaphor and metaphors for most modern
apps and devices.
For now, I have placed a message where the OK and Buttons were
previously, to help existing users understand the change. In time, I
expect us to be able to remove that message entirely.
11a2cf53c5