pyOpenPASS improvements II

• make approximation operator in queries work with negative numbers
• count events only once per timestep
• allow unfiltered queries
• allow queries on RunStatistics
• allow single config in JSON file instead of config_set with one element
• code refactoring
• use TestCase and TestItem from pytest
• fix queries at spawn time

changed milestone to %Release vX.X.X

added Bug Enhancement Work In Progress labels

assigned to @rbiegel

created branch 146-pyopenpass-improvements-ii to address this issue

mentioned in merge request !87 (merged)

closed

removed Work In Progress label

changed milestone to %Release v0.10