Move touch inputs to a TouchController class to move some logic from the
iPhoneView class. Only do this for touches on screen since connected
trackpads can generate touches as well. The latter ones are of type
UITouchTypeIndirectPointer while touches on screen are of type
UITouchTypeDirect. They are separated thanks to the preference key
UIApplicationSupportsIndirectInputEvents set to YES in Info.plist.
Without the preference above, there is no way to distinguish touches
from screen from a trackpad.
