Move Plot initialization to __init__.
Migrating histogram source and ranges calculation from _charts.py to histogram.py.
Move histogram method into the histogram.py file
Migrated helper functions to ChartObject class.
Remove histogram-related old code from _charts.py.
Migration of bar, scatter and boxplot-related code from _charts.py to each specific chart_type file.
Migrated common attributes to the primary ChartObject class.
Abtracted get_data_ and get_source_methods.
Make Chart instantiation available at the ChartObject class, more abstraction.
Added docstrings to the Chart class.
Added docstring to all the charts available and the ChartObject class.
Removed self source and ranges, delete notebook detection leftover and added chained methods for scales.
More docstrings.
Moved _set_and_get to each chart type.
Moved datarange, range and groups as parameters in each chart type.
Another round of styling to the docstring.
Merged-in master, fixed conflicts.
Fixed backticks and datetime.
Fixed more docstring ans typos as Bryan suggested.
Do not document 'private' args in docstring.