FIX: Bug in threshold tollerance calculation for determining similarity

[anjsimmo]

Consider the following lines:

        t = ...
        x = abs(condition1.threshold - condition2.threshold)
        ...
        return 1 - (x / t) if x < t else 0

As x (the difference between the two thresholds) is a ratio of t, then t should be the tollerance above which two thresholds are considred different. The tollerance may be proportional to the threshold, e.g. PERMISSIBLE_DELTA * condition1.threshold, but PERMISSIBLE_DELTA * condition1.threshold + condition1.threshold makes no sense (e.g. consider the case where condition1.threshold is negative).

[sankhya10]

Hi @anjsimmo ,
LGTM, the absolute value works for various scenarios.
I will get it merged.