Add support for EVA calculation

[carlobortolan]

Given B/S and I/S:

1. Calculate WCR = Current Assets + short term non-interest bearing debt (NIBL)
2. Calculate IC = WCR + long term assets Total Assets - short term NIBL`
3. Calculate avg IC
4. Calculate NOPAT = Operating Income + Interest Income - provisional Income from Taxes - Tax shield (=Interest Expenses * Tc) = Interest Expenses Net Income * (1 - Tc)
5. Calculate EVA = NOPAT - WACC * avg IC

Optionally include EVA adjustments:

• Using sinking funds depr instead of straight line
• Capitalizing R&D expenses (IFRS)
• Recognizing operating leases as debt financing