Base: split export/import macros from FCConfig.h and move them to FCGlobal.h

The FCGlobal.h can be included in a Global.h header file of an extension module.

The reason is that some IDEs (e.g. QtCreator) fails to detect the export/import macros when only defined in the PreCompiled.h files and thus raise a parser warning.

src/Mod/Image/Gui/ImageView.h

@@ -25,6 +25,7 @@
 #else
 #include "GLImageBox.h"
 #endif
+#include <Mod/Image/ImageGlobal.h>
 
 class QSlider;
 class QAction;