bugfix [#23148] "ImportError: __import__ not found" on changing Render FPS

The BGE was getting the namespace dict directly from __main__ which conflicts
with my recent fix to get the pickle module working which to overwrote the __main__ module on script execution.

Simple fix is to have the BGE and Blender use the same method of getting namespaces.
Renamed CreateGlobalDictionary() to bpy_namespace_dict_new() and moved into bpy_internal_import.c

pickle still wont work in the BGE since we make a copy of __main__ namespace but for speed would rather not have to replace the __main__ module many times per second.

source/blender/python/generic/bpy_internal_import.c

@@ -350,3 +350,26 @@ void bpy_text_clear_modules(int clear_all)
 	Py_DECREF(list); /* removes all references from append */
 }
 #endif
+
+
+/*****************************************************************************
+* Description: This function creates a new Python dictionary object.
+* note: dict is owned by sys.modules["__main__"] module, reference is borrowed
+* note: important we use the dict from __main__, this is what python expects
+  for 'pickle' to work as well as strings like this...
+ >> foo = 10
+ >> print(__import__("__main__").foo)
+*****************************************************************************/
+PyObject *bpy_namespace_dict_new(const char *filename)
+{
+	PyInterpreterState *interp= PyThreadState_GET()->interp;
+	PyObject *mod_main= PyModule_New("__main__");	
+	PyDict_SetItemString(interp->modules, "__main__", mod_main);
+	Py_DECREF(mod_main); /* sys.modules owns now */
+	PyModule_AddStringConstant(mod_main, "__name__", "__main__");
+	if(filename)
+		PyModule_AddStringConstant(mod_main, "__file__", filename); /* __file__ only for nice UI'ness */
+	PyModule_AddObject(mod_main, "__builtins__", interp->builtins);
+	Py_INCREF(interp->builtins); /* AddObject steals a reference */
+	return PyModule_GetDict(mod_main);
+}

source/blender/python/generic/bpy_internal_import.h

@@ -60,5 +60,7 @@ extern PyMethodDef bpy_reload_meth[];
 struct Main *bpy_import_main_get(void);
 void bpy_import_main_set(struct Main *maggie);
 
+/* name namespace function for bpy & bge */
+PyObject *bpy_namespace_dict_new(const char *filename);
 
 #endif				/* EXPP_bpy_import_h */