elm: Remove some eo files from installation

elm: Remove some eo files from installation

These are some of the EO files that shouldn't be part of the public
EO API:
- elm_access (old)
- actionslider
- bubble
- diskselector
- flipselector (a fancy spinner)
- hoversel (use combobox instead)
- icon (use image instead)
- inwin
- naviframe (unreplaced for now)
- photo (use image)
- prefs
- segment control
- separator
- slideshow
- thumb (use image)

Note: This breaks the use of the elm_widget_xxx.h headers. Those
      were internal headers anyway. Exposed because of a lack of
      a proper inheritance API.