QmlDesigner: Add image cache

The image cache is saving images and icon of this images in a sqlite
database. If there are no images they are generated in the backgound.
The icons are fetched by item library.

Task-number: QDS-2782
Task-number: QDS-2783
Task-number: QDS-2858
Change-Id: I5a32cccfef7f8fd8eb78902605a09f5da18ce88e
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

share/qtcreator/qml/qmlpuppet/qml2puppet/qml2puppetmain.cpp

@@ -42,9 +42,11 @@
 #endif
 
 #ifdef Q_OS_WIN
-#include <windows.h>
+#include <Windows.h>
 #endif
 
+namespace {
+
 int internalMain(QGuiApplication *application)
 {
     QCoreApplication::setOrganizationName("QtProject");
@@ -138,6 +140,7 @@ int internalMain(QGuiApplication *application)
 
     return application->exec();
 }
+} // namespace
 
 int main(int argc, char *argv[])
 {