XMIDI: Forget old loop points when changing track

This fixes warnings that would appear after a little while in
Kyrandia 2, which would happen because every time the music
changed it would add a new loop point. This was probably harmless
because once the list was full it would keep re-using the last
element, and I imagine all songs were set to loop forever. But
this should be more correct, as I understand it.
DREAMWEB: Changed Italian LOGON command

Changed REGISTRA to ACCEDI for better user convenience.