Add sort methods
Add Kodi sort methods depending on the type of the window. Consequently the methods that were used to sort manually the items are removed: now we rely only on the Kodi's sorting methods.
Note: for Kodi < 19, the accented characters are listed after z so when the first letter is é it is replaced by e to have more natural sorting. (More information here)
Also create a "_set_title" method to decrease the number of actions done in the body "of generate_list_of_items"
Edited by Thomas