Video tutorials for getting started

People prefer to watch short tutorial videos instead of reading tips and so on. Current Welcome screen should be replaced with a set of short video tutorials. As first step, let's take the current training material and break that in to few minute long steps that can be video'd and posted to YouTube as series of "how to get started with Qt 3D Studio" material. Once we have these videos we can look in to linking those to be part of the welcome screen.