test that tests the original code
more functional version
remembered to initialise the value of the sliding window
Got sliding window with max to work in a naive version.

Changed the calls from eep_window_sliding to include the old or new window for accummulate, respectively compensate.

eep_window_sliding is now a gen_server.

@todo: must propagate the change of passing the window along to other modules - only eep_stats_max uses this approach right now. Could be that the behaviour's API should be changed.