Add ability link between categories from past month

[GoogleCodeExporter]

Currently, when user creates a new page, category information is copied but 
there is no linking between the category and the category from the origin page. 

If we store linking between a category on page A to a category on Page B, then 
we can use to lookup past expense items and use it to auto-populate the expense 
names, or to draw interesting graphs such as past-expense lines to compare this 
month's expense rate.

Original issue reported on code.google.com by soichih on 25 Aug 2011 at 2:56

[GoogleCodeExporter]

After linking categories over several monthes, it could exist a new page that 
had the year ballance (auto-updated).

Original comment by ppa...@gmail.com on 15 Nov 2011 at 3:56

[GoogleCodeExporter]

This feature will be part of 2.0.23.

Original comment by soichih on 27 Mar 2012 at 2:15

• Changed state: Fixed