bone.plot(user_color=None, mesh=False, PCA_inv=False, PCA=True)
Plot voxels with optional PCA, and colours
user_color (tupple): RGB color of the bone where 1 is maxium
eg: red = (1,0,0)
PCA (boolean): plots the PCAs of the voxel
PCA_inv (boolean): plots the inverse of each PCA so the axes go in both directions