Add MODNet model (#11)

* Add MODNet for portrait matting

* Minor fixes

* Move assets to home directory

* Add colormap

* ci

* Update README.md

examples/modnet/README.md

@@ -0,0 +1,15 @@
+## Quick Start
+
+```shell
+cargo run -r --example modnet
+```
+
+## ONNX Model
+
+- [modnet-dyn](https://github.com/jamjamjon/assets/releases/download/v0.0.1/modnet-dyn.onnx)  
+
+
+
+## Results
+
+![](./demo.png)

examples/modnet/main.rs

@@ -0,0 +1,23 @@
+use usls::{models::MODNet, Annotator, DataLoader, Options};
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    // build model
+    let options = Options::default()
+        .with_model("modnet-dyn.onnx")?
+        .with_i00((1, 1, 4).into())
+        .with_i02((416, 512, 800).into())
+        .with_i03((416, 512, 800).into());
+    let model = MODNet::new(&options)?;
+
+    // load image
+    let x = vec![DataLoader::try_read("./assets/portrait.jpg")?];
+
+    // run
+    let y = model.run(&x)?;
+
+    // annotate
+    let annotator = Annotator::default().with_saveout("MODNet");
+    annotator.annotate(&x, &y);
+
+    Ok(())
+}