Income statement proj input
Created by: chenzheng06
Add 2 income statement related calculations: income_statement_form_hist.py, forming historical income statement with UI inputs and bill overview. income_statement_next, projecting income statement for next year, with growth_rate_flag indicated from UI.
Add supporting functions in financial_lib: organize_bill_overview, calculating average annual bill with available inputs. convert_income_statement_class, converting an Income_Statement class into dictionary format Income_Statement class, to easily define instance and related methods.
Minor update in libs, and minor update on sample data.