Implement persisting UI states

[tech-bash]

Fix: #140

I have started the task, please let me know if I am going in the right direction. Just for my check the moveEvent doesn't have any size() function it has QPoint so to avoid the implications I set them_savedSize type to QVariant would that be okay?

[tech-bash]

@mortbopet any comments sir?

[mortbopet]

I don't think there's a need to store the size and state in in-memory variables. Instead, you should call RipesSettings::setValue within the events.
Secondly, there's two parts to UI state persistence - one is storing the current state whenever it changes, the other is that you need to load said state upon program startup (i suggest that you analyse some of the other usages of RipesSettings throughout the codebase to get a feel for this).