First step of refactoring.

My goodness! I think that this library needs huge amount of works and refactoring.

My comments:
* I prepared another template of files and directories. In my opinion more logical.
* Library composed in that way can be used in qmlscene and any qt quick application: a) "qmlscene qmlscene main.qml -I ." (in same directory you should have folder with compiled library); b) you can use QQuickView as always and declare plugins directory with QQmlEngine::addImportPath; c) you can install plugin inside yours system;
* In future qt pro project probably should be replaced with cmake. But at the moment it will be easiest for everyone to use tools available directly with Qt SDK. 
* This is only preview. You can merge it or not. I don't understand all of yours decisions. In yours code I saw many "dirty" solutions. In theme, units and other helper class especially. Its should be pretty easy for you to extend my sample code and make yours library more understandable.
* At the moment we have here regresion. But it is necessary in my opinion.