Fixed thermostat applied on wrong number of cell layers

[Thinkpiet]

fixes #78

[Thinkpiet]

Background:
In old MaMiCo versions, datastructures::MacroscopicCells::applyXLayersOfGlobalNonGhostCellsWithLinkedCells() used to call apply() on X+1 layers. Thus, the thermostat configuration for type=outerLayers used to pass X-1 layers, to compensate.
When refactoring to new index system, we fixed this, so that
datastructures::LinkedCellContainer::applyXLayersOfGlobalNonGhostCellsWithLinkedCells() now actually uses X layers. However, since thermostat configuration was still doing the X-1, number-layers="1" caused the thermostat to be turned off completely. This causes the fluid to cool down, spontaneously decompose, regions without particles yield the zero values in the filter which were mentioned in #78