Create a user-facing interface CLI

Previously, those that did not perfectly match were discarded and left unconnected.

* DataDependencyArc: change style
* Exit/ReturnNode: removed variable extraction
* ESCFG: removed the method call as an exception source.

Other changes: corrections, improvements and API simplification

OUT nodes not generated for primitive types or literals

Added support for node subtypes

* Includes minor fixes to slicing criterion and slice to AST conversion
* Minor changes in logging, to avoid logging without error/warning

Side-effect: PDGTests cannot access GraphLog.

Added output node to method declaration + changed return to output

WIP: Added Naive summary arcs builder

Organize NodeType enum

* Added METHOD_EXIT
* Renamed METHOD to METHOD_ENTER
* Split VARIABLE_IN into FORMAL_IN and ACTUAL_IN.
* Split VARIABLE_OUT into FORMAL_OUT and ACTUAL_OUT.
* Removed exitNode from CFG and corresponding methods.

Resolve 6-method-call-nodes