Add documentation to all existing functions

[DanielNobbe]

Add or expand function and code descriptions. For each function:

• Arguments
• General description
• Discussion of implementation or areas for improvement, if applicable For each class:
• Attributes
• General description
• Discussion of implementation or areas for improvement, if applicable For each (python) file:
• General description of code it contains

[DanielNobbe]

• [x] modules
  • [x] info/retrieval
    • [x] __init__.py
    • [x] classes.py
    • [x] definitions.py
    • [x] history.py
    • [x] preprocessing.py
    • [x] tools.py
  • [x] analysis/covariance.py
  • [x] trader
    • [x] interpreter
      • [x] __init__.py
      • [x] interpreter.py
      • [x] safe.py
      • [x] safety.yaml
    • [x] predictor
      • [x] __init__.py
      • [x] predictor.py
  • [x] training
    • [x] models
      • [x] RNN.py
      • [x] __init__.py
      • [x] markov_kernel.py
      • [x] markov_kernel_1n.py
    • [x] trainer
      • [x] brock.py (+ rename/delete)
      • [x] ketchum.py (+ rename/delete)
      • [x] misty.py (+ rename/delete)
      • [x] trainer.py (+ rename/delete)
        • [x] __init__.py
• [x] config files
• [x] libs/API
  • [x] Oanda.py (+ capitalisation to small)
  • [x] Order_Position_Book.py (+ capitalisation to small)
  • [x] Orders.py (+ capitalisation to small)
  • [x] WorkingFunctions.py (+ capitalisation to small)
  • [x] __init__.py
• [x] scripts/main.py
• [x] tests
  • [x] Train_Model.py (+ capitalisation to small)
  • [x] Train_Model_V2.py (+ capitalisation to small)
  • [x] Train_Model_V3.py (+ capitalisation to small)
  • [x] Train_Model_V4.py (+ capitalisation to small)
  • [x] test_predictor.py