Optimization in KDE Base
* this introduces a Theme object used by Svg to cache the rendering of svg's asking to be colorized, but which are not part of the theme. this requires an independent cache and set of color files, therefore a second Theme object.
* not dropping the cache just because we change themes; this made sense when just plasma-desktop used this or when the apps using Plasma::Theme all used the same theme. this is no longer the case, really, and having applications changing themes randomly kicking the cache out from underneath other apps that may still be using it is undesirable. this does mean that cache files will accumulate. not sure that's a big issue as they don't tend to be large and are in an area marked as "cache" (so ripe for clean-without-care)
* cleanups such as getting rid of superfluous use of Plasma:: namespacing in code that is now in libplasma, such as the stylesheeting. (it was from a plasmoid sebas wrote originally, iirc, explaining the historical reason for the explicit namespacing)