remove unused wind argument to avoid confusion

Author: gauteh

opendrift/readers/reader_current_from_drifter.py

@@ -25,7 +25,7 @@
 class Reader(BaseReader, ContinuousReader):
     variables = ['x_sea_water_velocity', 'y_sea_water_velocity']
 
-    def __init__(self, lons, lats, times, wind=None, waves=None, z=0,
+    def __init__(self, lons, lats, times, waves=None, z=0,
                  name='reader_current_from_drifter'):
         """Reconstruct currents from time series of drifter positions"""