default plasma theme and fallback

[Ivan Čukić]

Just another thing.

The problem mainly arose from the fact that we use the /name/ of the directory 
as an identifier which decides whether the theme is the default one.

So, we would still have this problem after this patch (which still gets +1 
from me even with this problem).

How to make a theme that is based on Air? If you put FallbackTheme=default - 
you have done nothing. If the default theme changes (again), it will lead to 
breakage yet again.

With icons, we use symbolic link default -> oxygen (or default.kde4 -> 
oxygen). What about using something similar here?

Cheerio