Using Plasma::Svg outside of Plasma

[Manuel Mommertz]

I looked a bit deeper in the code and there are some more things that need a 
bit of work in my eyes:

Currently Plasma::Theme::styleSheet takes its colors always from defaultTheme 
instead of the Theme it is called from. This is very easy to fix.

If a Plasma::Svg is not themed it stores its pixmaps in the cache of 
defaultTheme. For this, it would be a better solution to have a generic 
systemTheme or something like that, as there is no need to rerender this, if 
the default theme changes. Beside this, there is really no logical relation 
between an unthemed svg and the default plasma theme.

To conclude: I still think that a generic Plasma::Theme would be the best way 
to solve this issues. But I am open to other solutions.

I am going to create a working patch for this until next sunday but as i can 
only work on weekends and there might be other private stuff, this might take 
longer.