Optimize case loading time dramatically for large plans

Signed-off-by: MHesham <mhesham.fcis@gmail.com>
Remove OpenGL reference, and add 1 more rendering hint for more smooth drawing

Signed-off-by: MHesham <mhesham.fcis@gmail.com>
Remove useless check at GraphEdgeView paint method

Signed-off-by: MHesham <mhesham.fcis@gmail.com>
Fix bug of the GraphNodeView displays the ID of the planstep not the Node inside its graph

Signed-off-by: MHesham <mhesham.fcis@gmail.com>
Fix the bug of NodeEdges position is not updated on moving a node

Signed-off-by: MHesham <mhesham.fcis@gmail.com>