Update dtoh_sync_copy

[zjsec]

pub fn dtoh_sync_copy<T: DeviceRepr>(
    self: &Arc<Self>,
    src: &CudaSlice<T>,
) -> Result<Vec<T>, result::DriverError>

Would it be better to modify it to the following?

pub fn dtoh_sync_copy<T: DeviceRepr, Src: DevicePtr<T>>(
    self: &Arc<Self>,
    src: &Src,
) -> Result<Vec<T>, result::DriverError>

[Corey Lowman]

Yes I think that'd be a nice improvement