VOYEUR: Replaced original game mansion scrolling with a more effective one

The original had the cursor fixed in the middle of the screen, and
scrolled the mansion view as the mouse moves. Since this doesn't really
work for windowed mode nor tablets, I've replaced it with a new version
that scrolls when the mouse cursor is near any edge of the screen
VOYEUR: Fix names of cursor variables in doInterface
VOYEUR: Fix loading of correct hotspot list in doInterface
VOYEUR: Workaround for original code causing crash after calling doEvidDisplay
VOYEUR: Tweaked vertical scroll area/rate for viewing mansion