GUI: Use sorted file list in scummtheme.py.

This will (hopefully) reduce the amount of changes when recreating the themes
because the order in which files will be processed is the same unless the
sorting differs on systems...
GUI: Recreate default theme.
MADS: Fix palette corruption when changing selected inventor item
MADS: Fix restoring upper palette area when dialogs close
IPHONE: Scale input according to content scale factor.

This hopefully fixes input positions in retina devices. The idea is stolen
from QT: https://qt.gitorious.org/qt/qt/source/0726127285413829f58618b5b82fb3e2da0c3a74:src/plugins/platforms/uikit/quikitwindow.mm#L261-296

Complicated way to retrieve scale's return value properly is taken from:
https://stackoverflow.com/questions/3130464 We sadly can't use the cleaner
solution since we don't want to require a newer SDK...
MADS: remove a magic value, use _transparencyIndex
MADS: Fix an uninitialized variable in DialogsNebular
CRUISE: Remove logically dead code in Sound
CRUISE: Remove useless code in addAnimation()