TemperatureControlPool: fix off-by-one in pool_index
Module: remove unused kernel pointer, shrink every Module instance by 4 bytes
Don't chain header includes if we don't have to, use predeclaration if we only need pointers. Include necessary headers from implementation rather than declaration.
Robot: remove current_position as it's substantially similar to last_milestone and can be completely replaced by this slight rework of append_line()