move rust to root, make a separate main example, start using iterator

examples/main.rs

@@ -0,0 +1,11 @@
+use thermaldecoder::decode_raw;
+
+use std::env;
+
+fn main() -> anyhow::Result<()> {
+    let mut arg = env::args();
+    let filename = arg.next().ok_or(anyhow::anyhow!("unexpected"))?;
+    let frames = arg.next().unwrap_or("frames".into());
+    decode_raw(&filename, &frames)?;
+    Ok(())
+}