Replace tracing with log (#2928)

* Replace tracing crate with log

It's just so much simpler to use

* Add `bacon wasm` job

* eframe: add a WebLogger for piping log events to the web console

crates/egui_demo_app/Cargo.toml

@@ -37,7 +37,7 @@ egui = { version = "0.21.0", path = "../egui", features = [
 egui_demo_lib = { version = "0.21.0", path = "../egui_demo_lib", features = [
   "chrono",
 ] }
-tracing = "0.1"
+log = { version = "0.4", features = ["std"] }
 
 # Optional dependencies:
 
@@ -58,10 +58,9 @@ serde = { version = "1", optional = true, features = ["derive"] }
 
 # native:
 [target.'cfg(not(target_arch = "wasm32"))'.dependencies]
-tracing-subscriber = "0.3"
+env_logger = "0.10"
 
 # web:
 [target.'cfg(target_arch = "wasm32")'.dependencies]
 console_error_panic_hook = "0.1.6"
-tracing-wasm = "0.2"
 wasm-bindgen-futures = "0.4"

crates/egui_demo_app/src/apps/custom3d_glow.rs

@@ -89,7 +89,7 @@ impl RotatingTriangle {
             let program = gl.create_program().expect("Cannot create program");
 
             if !shader_version.is_new_shader_interface() {
-                tracing::warn!(
+                log::warn!(
                     "Custom 3D painting hasn't been ported to {:?}",
                     shader_version
                 );

crates/egui_demo_app/src/lib.rs

@@ -52,7 +52,7 @@ pub fn init_wasm_hooks() {
     console_error_panic_hook::set_once();
 
     // Redirect tracing to console.log and friends:
-    tracing_wasm::set_as_global_default();
+    eframe::web::WebLogger::init(log::LevelFilter::Debug).ok();
 }
 
 #[cfg(target_arch = "wasm32")]

crates/egui_demo_app/src/main.rs

@@ -15,8 +15,8 @@ fn main() -> Result<(), eframe::Error> {
         std::env::set_var("RUST_LOG", rust_log);
     }
 
-    // Log to stdout (if you run with `RUST_LOG=debug`).
-    tracing_subscriber::fmt::init();
+    // Log to stderr (if you run with `RUST_LOG=debug`).
+    env_logger::init();
 
     let options = eframe::NativeOptions {
         drag_and_drop_support: true,