[+] StbMainApp: playlist_editor: Ask for save bouquet on exit from playlist editor if something changed

Signed-off-by: Anton Sergeev <Anton.Sergeev@elecard.ru>
[*] StbMainApp: Fix compilation error when using linux lists in c++ (uses new keyword)

Signed-off-by: Anton Sergeev <Anton.Sergeev@elecard.ru>
[*] StbMainApp: Move string list API into helper

Signed-off-by: Anton Sergeev <Anton.Sergeev@elecard.ru>