positioning: Calculate sizes instead of storing, move position out of widgets

Sizes of widgets can be derived, so storing them was only for C compatibility. Similar with storing position inside of widgets.

Some layout margin and scaling changes could be introduced, meaning a possibility of visual differences.

eek/eek-xml-layout.c

@@ -34,6 +34,5 @@ eek_xml_layout_real_create_keyboard (const char *keyboard_type,
                                      enum squeek_arrangement_kind t)
 {
     struct squeek_layout *layout = squeek_load_layout(keyboard_type, t);
-    squeek_layout_place_contents(layout);
     return level_keyboard_new(manager, layout);
 }