Object flow and trees

See merge request !58

* Some assertions changed to Illegal{State,Argument}Exception.

* Unified both summary arc analyzers
* Deleted unused code.
* Converted checks into assertions
* Removed some bad patterns, including a possible bug in BinaryExpr handling.

If a variable is provided, only nodes that represent that variable (or its MemberNode, if object) will be selected.

Related tests updated.

this test requires improved variable targeting

When searching for interprocedural actions, don't generate trees for variables that don't have them.

Redesigned JSysCallConnector, to rely more on CallConnector.

Add Structural arcs to avoid stopping the traversal when a pseudo-predicate (i.e. return) has objects connected to it.

Add value dependency between the active exception definition and its throw/exception return statement.

Group actions before applying the ExpressionObjectTreeFinder and make grouping actions by root idempotent.