Architecture refinement for 0.2

[gnuheidix]

Imho, we should refine our architecture for release 0.2 in order to have less dependencies between the classes. Especially dcm4che is a problem for our architectural quality. E.g. plug-ins shouldn't depend on that external library. The whole application would get a huge problem if that library did something bad in a future version.

[nostroh]

Well thats always the problem when using external libraries. The whole application depends on them but I don't see how to change that with a reasonable effort.

[gnuheidix]

Maybe Dicomux itself could use dcm4che and the plug-ins would receive their data from the application. Dicomux could do the communication with dcm4che and the plug-ins would be independent from any external libs. Some effort would be needed to realize that mechanism and Dicomux wouldn't be faster afterwards. We have to decide whether it is worth it or not.

[gnuheidix]

Referring to the Google Clean Code Talks, we have to do much refactoring. Especially the null and switch keywords have to be replaced by better approaches. Keywords: polymorphism, dependency injection. Our classes simply do too much stuff. The whole code isn't testable at all.