* simplify eina_stringshare usage with _eina_stringshare_replace();
* do not modify the string in stringshare as in e_fm2_parent_go();
* use custom_theme_content instead of custom_theme in e_fm2_custom_theme_content_set().
Hopefully this will break nothing, but further analysis if it's
leaking strings in the stringshare should be done.
SVN revision: 38559