Use a subtler error message that displays in the same place as the
loading message but does not change the entire background of the
view.
Also, extending classes can now customize the message displayed
when there are no items and also no filtered items to allow for
different messages for these two cases.
This will be a style that can be used by extending
classes to provide two lines that don't wrap with
color and padding.
This is initially used by symbols view and fuzzy finder.
