chg: display of knowledge entities
chg: improved debug logging
add: improved validation: compare nexus of relation and parameter
add: isStringValue()
add: explicit tests for String-Feature-Values
FIX: getConstantFeatureValue() and getVariableFeature() must use
Param-Value, not Param-ID
add: counter for iterations in order to avoid endless loops
add: new and improved logging
fix: consider feature-id when cleaning choices of a knowledge entity
fix: knowledge is not stable if evaluateXXX() removed some values
add: handling of unfulfillable choices
add: validation of operator and its complement
FIX: transformation from xml relation type to relation operator
add: improved logging
fix: handling of right relation parameter
add: improved logging