Adapted code to method name change from GCTAObservation::hasresponse() to GCTA_Observation::hasresponse()
Correctly take RoI and livetime variations in background computation into account.

The background models are now livetime weighted before addition, and only event bins are filled that fall within the RoI of the corresponding event list.
Remove prefix parameters and make sure that bins outside RoI are not filled.

We do not want to fill cube bins outside the RoI to be consistent with the response and modelling part.
Remove protected methods from interface.
Correct typos
Add stacked cube analysis script.

The purpose of the make_cube_analysis.py script is to provide an end-to-end test fur stacked cube analysis. It uses 4 CTA observations to illustrate the usage of stacked cube analysis and to demonstrate that the fitting results are okay.
Clean-up public method interface.