Status variables are only saved at module deactivation

[tobiasgehring]

Status variables are saved to file at module deactivation. This means that if Windows or Qudi crashes new settings are lost.

Expected behavior (i.e. solution)

Status variables should be saved immediately.

##Other Comments @a-stark pointed out that it is important that not all status variables are saved when only one is changed since status variables may include potentially big numpy arrays. They should only be updated when they are changed explicitly.