Macroeconomic data sandbox

lab.py can now:

• read data from local csv file
• create pandas dataframes using Indicator class
• plot time series and saving them to Excel file

Now working:

• groups of variables
• separate names for groups of variables

May need:

• add df directly to Indicator class

Ideas:

• Indicator() to replace KEP() class
• New KEP package structure

Enhancements:

• better graphs
• first column formatting in xls
• several sheets in xls file

May use plotting archives:

• https://github.com/epogrebnyak/plotting
• https://github.com/epogrebnyak/data-rosstat-kep/blob/master/kep/getter/plots.py