Implement Logic in Symbol layer

[amis92]

ILogicSymbol is a parent type of the following:

• IConditionSymbol (BS Condition/ConditionGroup)
• IConstraintSymbol (BS Constraint)
• IEffectSymbol (BS Modifier/ModifierGroup/Repeat)
• IQuerySymbol (BS Modifier/Constraint/Condition's Query+FilterBy+Condition common abstraction)
• IQuerySymbol and IEffectSymbol bindings of the field/scope/filter(child) IDs.

I've settled on a tiny simplification - modifier(group) and repeat are an Effect, condition(group) is Condition, and Query is a common part of querying in constraint, condition and repeat:

• IEffectSymbol is either a modifier, modifier group or a repeat BS element unified into a single interface. May contain a Condition, and a RepetitionQuery. Entries contains Effects (modifiers/modifier groups) and an Effect can contain other Effects (repeats), as well as ChildEffects (in modifier group).
• IConditionSymbol is either a condition or condition group BS element. Contains Query. Effects can contain up to a single Condition, and Conditions can have Child conditions that are evaluated using and/or operator.
• IConstraintSymbol is a constraint BS element. Contains Query, but signifies a boundary/limit. Entries contain Constraints.
• IQuerySymbol - is an abstraction over querying in conditions, constraints and repeats. It defines a Value (field) that is counted, a Scope in which elements are counted, and a Filter which takes only specific elements to count. Then the results are processed - if query defines a ComparisonOperator, the query result is compared with ReferenceValue - otherwise the numeric sum of values is returned.

[amis92]

Implementation of symbols was in 54e12b3

[amis92]

Deep investigation into Querying was done in #45