Added the ability to use a custom favicon.

tasks.py

@@ -1,5 +1,6 @@
 import asyncio
 import io
+import shutil
 import tarfile
 from contextlib import contextmanager
 from pathlib import Path
@@ -45,7 +46,12 @@ def compile_scss(ctx, watch=False):
     # type: (Context, bool) -> None
     from app.utils.favicon import build_favicon
 
-    build_favicon()
+    favicon_file = Path("data/favicon.ico")
+    if not favicon_file.exists():
+        build_favicon()
+    else:
+        shutil.copy2(favicon_file, "app/static/favicon.ico")
+
     theme_file = Path("data/_theme.scss")
     if not theme_file.exists():
         theme_file.write_text("// override vars for theming here")