(graphics): Qt3D generic scene and mesh visualization integration

Description

Implement basic qt3d rendering services:

• Generic scene service
• Mesh visualization service
• Examples in XML, Cpp and QML

Generic scene service:

• ::fwRenderQt3D::GenericScene object handling a qt3d scene
• ::fwRenderQt3D::FrameGraph object to attach to a GenericScene, allowing to define custom qt3d framegraphs
• ::fwRenderQt3D::SRender service used to define a GenericScene object within Sight context and attach adaptors to it

Mesh visualization service:

• ::fwRenderQt3D::Mesh object creating a mesh from sight data using qt3d geometry renderer
• ::fwRenderQt3D::IAdaptor class providing base functionalities for Qt3D adaptors.
• ::fwRenderQt3D::SMesh adaptor used to create a qt3d mesh from sight data and attach it to the render service

Closes #519 (closed)

How to test it?

These features can be tested using one of these applications:

• TutoSceneQt3D
• TutoSceneQt3DCpp
• TutoSceneQt3DQml

These apps load a mesh (using Ctrl+O) and render it into a generic qt3d scene.