The different MyExport functions have been removed to use the equivalent
exportOnSpace functions of xPostProcessingManager, except for those
who are specific to Octree (this would require to introduce a dependency
of xExport to xOctree).

For now the exportOnTime functions are not used, because it would require
strong modifications (or in the worst case, full remove) of the
DamageCurveWriter concept. This is kept for a further commit.