Make cast_event unsafe

[maxbla]

/// Casts the generic event to the right event. Assumes that the given
/// event is really the correct type.
pub fn cast_event<'r, T>(event : &'r GenericEvent) -> &'r T {
    // This isn't very safe... but other options incur yet more overhead
    // that I really don't want to.
    unsafe { mem::transmute(event) }
}

This is the code for cast_event(). Safe functions should (almost?) always be safe, no matter their arguments. My suggested fix is to change it to

pub unsafe fn cast_event<'r, T>(event : &'r GenericEvent) -> &'r T {
    mem::transmute(event)
}

This signals to callers that they have to be careful when calling cast_event.

[rtbo]

cast_event is unsafe since 0.8.0.