[Feature] Open plugins now recognizes known filetypes and can run them

now you can run your lua files without having to add the viewer to
the shortcut or if you want a bmp file to be displayed when you start
the device that can be done as well

Change-Id: Ia56b566789623a2ca78d9e4583086db6e2cd689b

apps/plugin.h

@@ -974,6 +974,7 @@ struct plugin_api {
 #endif
     int (*playlist_get_first_index)(const struct playlist_info* playlist);
     int (*playlist_get_display_index)(void);
+    char* (*filetype_get_plugin)(int attr, char *buffer, size_t buffer_len);
 };
 
 /* plugin header */