do the mwait and re-init last-cr so that there no date irregularity.
Such a thing is necessary for dvd playback at cell change ; however,
Meuuh, could you look at that since you might think we should do
otherwise.

-turned the "bitsream callback discontinuity" message to debug.

-removed modification of the title environnement variable in input dvd
at title change since we no longer restart the input at title change.