- Previously, all types were considered possible. In reality, only a single method can be called (the first parent class that defines it).

Support for enums and static variables

See merge request !62

- Updated README.md
- New module for benchmarks (sdg-bench)
- Added representations for the original JSysDG and for the Allen&Horwitz SDG (graph and slicing algorithm)
- Fixed bugs:
  * Accept abstract methods (without a body)
  * Avoid generating constructors for interfaces
  * Handle calls outside methods
  * Handle methods inside methods
  * Locate and handle all method calls (including on the left-hand side of assignments and in return statements).
  * Correctly determining the type of -output- nodes
  * Various errors related to object tree location and traversal

Included javaparser-symbolsolver as module to solve bug with generic arrays resolution.

ObjectTree: make fields into arrays of Strings.

- The previous approach used a single string, with fields separated by dots.
- The inclusion of packages in class names thwarts the previous approach.

* Simple enums, with empty constructors.
* Initializations are not handled.

Assumptions: there are no circular dependencies in initialization of static variables and enums are immutable.

* Summary arcs are generated correctly for actual-out with multiple actions.
* Properly detect optional actions.
* Fix type insertion at incorrect level in object trees.
* Constructors may throw exceptions.
* Dynamic initializers are marked as implicit.
* The LHS of an operation assignment is included in the ExpressionObjectTreeFinder (e.g. `a += 10`).
* Admit calls from dynamic initializers.
* Removed unused utility methods.

ExpressionObjectTreeFinder will now locate the correct VA, by searching for the matching call or expression.

Slicing criterion can include a variable. Multiple criteria can be included for a single file.

Add polymorphic calls

See merge request !61

* Call targets are computed based on static types (same as variable action's dynamic types).
* Usage and definition finders now deal with accumulating information in the same variable action ('-arg-in-' or '-scope-in-'). That variable action is created in the VariableVisitor, and the transference is prepared at the end of the finder, instead of with each handleActualAction.
* ObjectTree: pattern now accepts any variable, including fake patterns like ('-root-' or '-arg-in-')
* Tests updated

# Conflicts:
#	sdg-core/src/main/java/es/upv/mist/slicing/nodes/VariableAction.java

* Some searches in object trees may return multiple nodes (e.g. "var.A.x" and "var.B.x" for "var.x")
* Only leaves in object trees can be the target of summary arcs.
* Polymorphic nodes aren't interconnected with data dependencies.
* ClassGraph's map now split into kinds of vertex.
* ClassGraph's vertex now generic.
* Polymorphic member nodes cannot be leaves in object trees.