{trunk] filter qty != 0 does not work correctly

[Ferdinand]

inventory analysis

 filter "equal 0" and "not equal 0" does not return correct results

I guess the beloved rounding issues :-((

[Borja López Soilán (NeoPolus) (borjals)]

The equality tests should be made with care when working with floating point numbers.

The easiest example on Python:

>>> 1.1 - 1 == 0.1
False

>>> round(1.1 - 1, 4) == round(0.1, 4)
True

[Borja López Soilán (NeoPolus) (borjals)]

Given the comment from Fabien on bug 656378 (commented on the wrong place) it seems that this bug is not a rounding problem but an usability problem: The filter "Qty is not equal to 0" is being applied to the records before grouping (WHERE), but the user interface seems to suggest that the filtering is done after grouping (HAVING).