VariableChooser: Rework

Allow multiple expanders to be registered for lineedits, e.g. a
local and the global ones, and actually show them.

Use a tree view in the chooser for somewhat more structured display.

Change-Id: I769f92144e5249f45e54381de52aa6973eb20118
Reviewed-by: Tobias Hunger <tobias.hunger@theqtcompany.com>

src/plugins/coreplugin/jsexpander.cpp

@@ -30,8 +30,8 @@
 #include "jsexpander.h"
 
 #include "corejsextensions.h"
-#include "variablemanager.h"
 
+#include <utils/macroexpander.h>
 #include <utils/qtcassert.h>
 
 #include <QCoreApplication>
@@ -90,7 +90,7 @@ QString JsExpander::evaluate(const QString &expression, QString *errorMessage)
 JsExpander::JsExpander()
 {
     d = new Internal::JsExpanderPrivate;
-    globalMacroExpander()->registerPrefix("JS",
+    Utils::globalMacroExpander()->registerPrefix("JS",
         QCoreApplication::translate("Core::JsExpander",
                                     "Evaluate simple Javascript statements.\n"
                                     "The statements may not contain '{' nor '}' characters."),