2) Created ExprNode::expressionEqual method to replace a new big and ugly switch.
3) Make boolean referencers use BoolExprNode instead of jrd_nod, except nod_validate for now. This includes BinaryBoolNode and NotBoolNode working without jrd_nod references.
4) Rework in the impure allocation code (replace "csb_impure += ..." by CMP_impure calls).
Convert CONCATENATE and aggregate functions to it.
Fix some bugs:
- select sum(n) over (order by n2), sum(n) over (), n, n2 from x1;
- select (select 1 from x1 b where list(1, a.n) = 1) from x1 a;