use env_logger in all examples (#2934)

examples/svg/src/main.rs

@@ -7,6 +7,7 @@
 use eframe::egui;
 
 fn main() -> Result<(), eframe::Error> {
+    env_logger::init(); // Log to stderr (if you run with `RUST_LOG=debug`).
     let options = eframe::NativeOptions {
         initial_window_size: Some(egui::vec2(1000.0, 700.0)),
         ..Default::default()