Made the Mangler file compile again

[lemio]

Mangler is the example file included in the IDE for developers that want to make their own tool. This mangler.java file is way outdated and didn't compile on the recent Arduino IDE pde.jar and arduino-core.jar

The .getCurrentTab() was missing, and for some reason it wouldn't compile with the isSelectionActive() , while I did find the file in https://github.com/arduino/Arduino/blob/master/app/src/processing/app/syntax/SketchTextArea.java . But at least people can compile it after these changes

src\Mangler.java:84: error: cannot find symbol
    if (editor.getCurrentTab().isSelectionActive()) {
                              ^
  symbol:   method isSelectionActive()
  location: class EditorTab
1 error

src\Mangler.java:73: error: cannot find symbol
      String selection = editor.getSelectedText();
                               ^
  symbol:   method getSelectedText()
  location: variable editor of type Editor
src\Mangler.java:86: error: cannot find symbol
      editor.setSelectedText(new String(stuff));
            ^
  symbol:   method setSelectedText(String)
  location: variable editor of type Editor
2 errors