Preference rework

[hinterwaeldler]

Hi,

while looking for something else, i've noticed that the code within the preference contains a lot of duplication. To avoid too much rework I've reduced the changes to a existing parts and moved the template stuff used into the cpp directly. In addition it's hard to implement the pod limitiation without the usage for c++11 parts, which I think are not supported from all compilers yet

As I'm not sure, that all compilers support this correctly maybe someone should check if this works for the ubuntu 12.04 parts.

Greets