Started to adapt the editor to use the Qt Renderer.

For now, I only broke the main editor by removing videomanager bindings,
but fully adapted the tileset editor.

I'll use this simple example to create the editor view in another commit.
Started to remove broken code from the main editor view.
Made the editor able to load and display a map.

To achieve this, I had to remove the scrollarea QWidget and merge it
into the Grid class. This permitted to let the scrollarea handled by the QGraphicsView.

Note that the editor still can"t handle mouse events for now.
Removed the now unnecessary dependency files when compiling the editor.
Remove some now useless compile flags in the engine files.
Readded mouse handling support. The editor is basically usable now.
Fixed new map creation crash by properly initializing layer data again.