Income vs. Expense Categories for Analytics

In v0.30.6, Tax categories were introduced but it is for Cash Flow analysis only; and in v0.30.9 Income categories were introduced but it is mostly for the transaction form.

My recommendation is to continue allowing the users to determine which categories belong to Tax and Income; however to apply such rules across all Analytics functions.

One typical example is that, though the Tax categories are treated separately in the Cash Flow, they are still considered as Expenses in the other Analytics modules (like Trend comparison, Pivot, FIRE, etc). This would significantly distort the outcome of financial analysis.