I have fixed the issue of wrong Theoretical Amount and Practical amount calculation in print budgets report

Steps to Reproduce:

1.  Create a Budget when duration 1st Jan 2014 to 31st Dec 2014.
2.  Create a budget line for Jan.  Budget Position: Purchases, Duration:  1st Jan 2014 to 31st Jan 2014,  Planned Amount: -30,000.
3.  Create a budget line for Feb. Budget Position: Purchases, Duration:  1st Feb 2014 to 28th Feb 2014,  Planned Amount: -10,000.
4.  Create a budget line for Mar. Budget Position: Purchases, Duration:  1st Mar 2014 to 31st Mar 2014,  Planned Amount: -10,000.
5.  Click “Print” à Print Budgets
6.  Start of Period:  28th Feb 2014,  End of Period:  31st Mar 2014, and the “Print”.
7.  Although all the planned amount is negative, the theoretical amount in the report is positive.