Replaced Point2D with Vector2, ArrayList with libgdx Array
(except when implementing java.util.List is required)
Generates a polygonal border for newly-created sceneElements
- this detailed border is shown only when object is selected
- the detailed border is used for collision detection
- lowered default threshold for border-detection

NOTE:
  if more uses of ShapeRenderer arise, we should use a similar
  approach to Drawable to pool these renderers. See
  https://github.com/libgdx/libgdx/issues/1186
Removed redundant collisionPolygons.clear()
Merge pull request #229 from manuel-freire/image-polygon-borders

Generates a polygonal border for newly-created sceneElements
Fixes #160 Added a simple tool to test UI widgets in tests. - Added TextArea test as use example
Merge pull request #243 from imartinezortiz/release-engineering

Updated Release engineering (changelog)
Added simple tests for geometryutils
Merge pull request #241 from anserran/widget-tester

Fixes #160 Added a simple tool to test UI widgets in tests.
Added TabsPanel widget
Fixed bug
Added the panel that will contain the options of action of the elements
Added new contructor method in TabsPanel widget and remove MoreElementComponent class
Introduced the panel where the conditions of an element for be visible are decided
Added i18n
Now the user can enter the name of the flag
Added FlagButton class for show a flag
Minor changes
Now the FlagPanel show the flags in a GridPanel
Javadocs and formatting.
Improved UI widgets.