text: Title: [NEW TRANSFORMER] exponential width discretiser
  Body: when a variable is in a logarithmic scale, it might make sense to create the intervals based on a log scale instead of linear scale.
  
  Quote:
  "
  When the numbers span multiple magnitudes, it may be better to group by powers of
  10 (or powers of any constant): 0–9, 10–99, 100–999, 1000–9999, etc. The bin widths
  grow exponentially
  "
  
  the idea is taken from: Feature Engineering for Machine Learning" Alice Zheng, O'Reilly.