Change relative to absolute import

Author: birgits

windpowerlib/turbine_cluster_modelchain.py

@@ -7,7 +7,8 @@
 __copyright__ = "Copyright oemof developer group"
 __license__ = "GPLv3"
 
-from . import modelchain, tools, wind_farm, power_curve, wind_turbine_cluster
+from windpowerlib import modelchain, tools, wind_farm, power_curve, \
+    wind_turbine_cluster
 import pandas as pd