Move all examples to their own crates (#201)

This makes it much clearer which dependencies each example has.

examples/templates/src/main.rs

@@ -0,0 +1,71 @@
+//! Run with
+//!
+//! ```not_rust
+//! cargo run -p example-templates
+//! ```
+
+use askama::Template;
+use axum::{
+    body::{Bytes, Full},
+    extract,
+    handler::get,
+    http::{Response, StatusCode},
+    response::{Html, IntoResponse},
+    route,
+    routing::RoutingDsl,
+};
+use std::{convert::Infallible, net::SocketAddr};
+
+#[tokio::main]
+async fn main() {
+    // Set the RUST_LOG, if it hasn't been explicitly defined
+    if std::env::var("RUST_LOG").is_err() {
+        std::env::set_var("RUST_LOG", "example_templates=debug")
+    }
+    tracing_subscriber::fmt::init();
+
+    // build our application with some routes
+    let app = route("/greet/:name", get(greet));
+
+    // run it
+    let addr = SocketAddr::from(([127, 0, 0, 1], 3000));
+    tracing::debug!("listening on {}", addr);
+    axum::Server::bind(&addr)
+        .serve(app.into_make_service())
+        .await
+        .unwrap();
+}
+
+async fn greet(extract::Path(name): extract::Path<String>) -> impl IntoResponse {
+    let template = HelloTemplate { name };
+    HtmlTemplate(template)
+}
+
+#[derive(Template)]
+#[template(path = "hello.html")]
+struct HelloTemplate {
+    name: String,
+}
+
+struct HtmlTemplate<T>(T);
+
+impl<T> IntoResponse for HtmlTemplate<T>
+where
+    T: Template,
+{
+    type Body = Full<Bytes>;
+    type BodyError = Infallible;
+
+    fn into_response(self) -> Response<Self::Body> {
+        match self.0.render() {
+            Ok(html) => Html(html).into_response(),
+            Err(err) => Response::builder()
+                .status(StatusCode::INTERNAL_SERVER_ERROR)
+                .body(Full::from(format!(
+                    "Failed to render template. Error: {}",
+                    err
+                )))
+                .unwrap(),
+        }
+    }
+}