Use of CString

[virtualritz]

I was just wondering. Is there any reason to prefer:

                let buf_name = CString::new("normal").unwrap();
                unsafe {
                    oidnSetSharedFilterImage(
                        self.handle,
                        buf_name.as_ptr(),
                        ...

Over

                unsafe {
                    oidnSetSharedFilterImage(
                        self.handle,
                        &b"normal\0" as *const _ as _,
                        ...

I'm still a Rust n00b but my gut tells me the latter will produce less code/have no runtime overhead.

[Twinklebear]

I didn't know about the byte string stuff actually, this might be nicer to migrate too

[virtualritz]

I have a PR for you then later today. I also added set_hdr_scale() since I needed that.

[Twinklebear]

Resolved in #10