implement support for i-dependent WS and WD in site and wt-dependent WS and WD kwarg to WindFarmModel.__call__

fix #44

fix "outside area" error occurring when making a flow map with XRSite (which fails because local wind at (0,0) is requested

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

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

add selfsimilarity blokage model
prepare for gradients
New structure. Old WakeModel mainly in new EngineeringWindFarmModel
add deflectionmodel
update documentation

- add missing h_i parameter in call from calculate_AEP
- update parqueFicticio grd files
- change site.probability function to take ws_bins instead of ws_bin_size
- correct probability calculation in WaspGridSite
- add test that compare WaspGridSite with results from Wasp (raw data, u_mean, air_power and aep)
- add function in OneTypeWindTurbines to instantiate from tabular data