TODO list for content aware resizing.

Speed:
- study how to perform "real time" seamcarving by using Lqr properly
- study parallelization of the carving process

Implementation:
- make the plugin thread safe

Gui:
- Add picture preview of the seams and of the energy
- Mouse wheel should change brush size
- Skin tones should be previewed as an orange mask

Features:
- Add more energy functions (prewit and sobel filter for instance)
- Add a button to rescale down and up automatically to remove the red mask