Add option to calculate AEP as described in the European Wind Atlas, page 95. This method calculate the power x weibull_weight using linear instead of constant power segments

Before the result of the GridInterpolator was transposed for 1 additional dimesion and mixed for more. This has been fixed

renamed GCLDeficitLocal to GCLLocalDeficit
renamed NOJDeficitLocal to NOJLocalDeficit
made NOJLocalDeficit subclass of NiayifarGaussianDeficit to reuse k_ilk function
add tests to test_deficit_models.py

add function to create XRSite from simulation_result.flow_box() allowing precalculated sites including effects of neighbouring farms