When we have several layers the casting is now done when the VR mode is activated, we do not append an image if its visibility is off -> improves interaction speed
[MUSIC] [CLUT_E] Corrects colors of LUT in discreteMode, a bit of cleanup
[MUSIC] [medClutE] Adds LUT inversion, improves vertex deletion, opacity rendering and thresholding with histo
Merge branch 'music' of https://github.com/LoicCadour/medInria-public into music