libgimbase: merge gimpparam.h into gimpparamspecs.h

which means that it's now included normally via gimpbase.h
and not any longer via gimpbasetypes.h which we only did out
of lazyness. A *lot* of files in libgimp* and app/ now need to

libgimpwidgets/gimpcontroller.c

@@ -24,6 +24,7 @@
 #include <gegl.h>
 #include <gtk/gtk.h>
 
+#include "libgimpbase/gimpbase.h"
 #include "libgimpcolor/gimpcolor.h"
 #include "libgimpconfig/gimpconfig.h"