Merge pull request #24 from andypiper/file-picker-update

main.js: only choose from image files

www/main.js

@@ -391,6 +391,7 @@ class CanvasController {
         }
         let input = document.createElement('input');
         input.type = 'file';
+        input.accept = 'image/*';
         input.addEventListener('change', () => {
             let url = URL.createObjectURL(input.files[0]);
             put_image(url);