[quantile regression project]  final modification. attempt to add multiprocessing. but results are not conclusive

[quantile regression project]  fix bugs in daily_observations.py for the creation of the coordinates for the daily fit. some fix to prepare for some potential non stationary exponential model one day

[quantile regression project] add test exp simulations (stationary and non stationary) for models on annual maxima. Prepare the code to fit with non stationary exponential models