Implementation of zenith dependence for classification

[GernotMaier]

Implementation of zenith dependence:

• remove size variable from training variables (most zenith dependent)
• add zenith angle as training variable or add zenith bin as training variable
• weight LZE and SZE events to get a flat zenith distribution in training
• stability tests for zenith dependence of the trained models; remove variables if needed

[GernotMaier]

implemented bins