a495, a810 and a1300 fixes from nafraf in http://chdk.setepontos.com/index.php?topic=650.msg98848#msg98848
- PROPCASE_DIGITAL_ZOOM_MODE added to propset3 and propset5 (tested on a495 and a810/sx260 respectively)
- A495, A810, A1300: CAM_USE_ALT_SET_ZOOM_POINT and CAM_USE_ALT_PT_MoveOpticalZoomAt defined.
- A495: stubs_entry_2.S cleanup and camera_set_led() fix.