xbmc doesn't provide status _ispaused_ from player. that means that
IsPlaying is returing True regardles to pause/unpause actions. because
we calculate and set xbmc process priority based on that, even if playback
is paused for hours, xbmc process will hold high priority a waste resources.

this change is keeping internal ispaused status set according to events
xbmc is sending (onpaused, onplay, onstop).

isplaying() is then considering paused status as well.
led definition are part of xbian-led service so clients setting led(s)
do not need to track complicated led definitions or take care of actual
platform. xbian-led decides this automatically.
verup