Efficient rendering of vector-based shapes and lines

- Stages replaced with EditorStage, in charge of a second ShapeRenderer pass
  (similar to the original SpriteBatch pass)
- Actors that wish to draw vector-based in this second pass must implement
  ShapeDrawable
- Replaced all "scaled empty boxes" with a 1 px border rectangle
- Fixes #148 (object-handles resizing themselves)
- Accesses Group's transforms to avoid additional transform matrix creation
partial changes message bubble
Revert "partial changes message bubble"

This reverts commit 84035a9c462c2c45d303e017750103c455743309.
Implementation of a simple dialog for showing information messages
Adaption of dialog and diallog controller for supporting modal dialogs and show/hide minize button
Test and main class
Fixed CombinedAction args valitity check.
Merge pull request #296 from RotaruDan/combinedActionFix

Fixed CombinedAction args valitity check.
Merge pull request #290 from manuel-freire/shape-rendering

Efficient rendering of vector-based shapes and lines
Modifications related pull request made by Angel Serrano
Merge pull request #295 from angeldelblanco/info-dialog

Info dialog