Added drag and drop widget
Docs about drag and drop
DragAndDrop widget test
Swing-based expression editor
* main class is the ExpressionEditor, in editor core tests
* supports both graphical editing (in tree) and textual editing (in textarea)
* required minor changes to Literals and VariableRef expression nodes
Some fix in docs. Remvoed unnecessary parameter.
Added test for modifier
Fix format
Merge pull request #385 from anserran/draganddrop

A fully functional drag and drop panel, with resize, rotate and move
Bindings generation now includes newlines, for ease of diff
Merge pull request #393 from manuel-freire/bindings-with-newlines

Bindings generation now includes newlines, for ease of diff
Merge pull request #389 from manuel-freire/swing-expression-editor

Swing-based expression editor
Cleanup of GeometryUtils and associated tester programs
* split off SchemaGdxConverter (engine) from GeometryUtils (editor-only)
* added ShapeEditor as stand-alone test (split from TexturedShapeEditor)
* updated GeoTester to use offsets, draw strings when required
Added perspective-corrected path-finding for polygons
* PathUtils contains general utilities (eg.: projection matrix manipulation)
* PathFinder finds the paths, allows path-segment iteration
* PathFinderTest contains JUnit tests for above
* PathTester contains a graphical test
Engine integration for path-finding
 * Path transformed by PathProcessor into PathComponent: poly+perspective
 * Goto effect executed by GoToExecutor adds WalkComponent: actual walking
 * PathSystem updates positions of elements with active WalkComponents
 * Integrated into cooldemo: click on alien to walk him around
Merge pull request #371 from manuel-freire/element-paths

Element paths
eAdventure Mockup bugfixes and adjustments after the recent refactoring.
Merge pull request #396 from RotaruDan/adjustments

eAdventure Mockup bugfixes and adjustments after the recent refactoring.
Fixes bad height calculation on window resize in AbstractWidgetTest
* also adds an array of "status" messages, useful in writing graphical tests
Merge pull request #400 from manuel-freire/abstract-widget-fix

Fixes bad height calculation on window resize in AbstractWidgetTest
Added LinearLayout as generalization of many others