Start of restructuring the application

For the graph module.
Problems with the creation during execution, and to access node's properties.
Delete not implemented yet.
Some modifications : test the node creation.

The current_node is not managed.
Problem with delete node.
Segmentation fault when quit application.
Use idNode to identify a node and a nodeWrapper.

Also manage current_node in graphWrapper.
Problem during destruction of one node : delete all nodes in QML, whereas the other nodeWrappers are still here.
Graph and GraphWrapper use Singleton class.
clean python import paths
Reorgonization with a new directory : ButtleOFX.

We can now launch buttleApp.py.
Already problems while destruction of nodes in the graph.
Rectification about Singleton.
source tree reoganization
add OpenGL viewer prototype
viewerGL proto: split code into functions
Update tree for Graph.

Use init python file to have more clear import (updated in all modules).
Env variable $PYTHONPATH is now :
PYTHONPATH=~/Documents/dev/ButtleOFX:$PYTHONPATH
PYTHONPATH=~/Documents/dev/ButtleOFX/QuickMamba:$PYTHONPATH
export PYTHONPATH
Fix QML errors when launch buttleApp.py

Yet one error, about the image loaded for the Player.
Fix currentNode feature for the graph.

=> creation and destruction of nodes for the graph work.
Yet a QML error for the image loaded for the Viewer (QUrl...).
Just moving the tools of the graph
Using QtDesktop for the layout
Connections management with the new architecture

bye bye ConnectionManager
improved identification of nodes

the identification was inconsistent
Fixed clip for the viewer
Fix problem of loaded image

But we need to differenciate the current image viewed and the current selected node !
simple click => node selected : we can modify its parameters
double click => change the image in the viewer
Modify the color of the current selected node

little bug to fix : when we create a new node, it is'nt automatically selected
Fix a bug on the node destruction

but there are still many bugs to fix