S allius/issue395 (#399)

* add button for languages setting

* build a web module for the dashboard

- load all python module from local dir
- initialize Blueprint and Babel

* set a default key for secure cookies

* add translations to docker container

* improve translation build  

- clean target erases the *.pot
- don't modify the resurt of url_for() calls
- don't translate the language description

* translate connection table, fix icon

* build relative urls for HA ingress

* fix unit test, increase coverage

app/src/web/favicon.py

@@ -0,0 +1,37 @@
+import os
+
+from quart import send_from_directory
+
+from . import web
+
+
+async def get_icon(file: str, mime: str = 'image/png'):
+    return await send_from_directory(
+        os.path.join(web.root_path, 'static/images'),
+        file,
+        mimetype=mime)
+
+
+@web.route('/favicon-96x96.png')
+async def favicon():
+    return await get_icon('favicon-96x96.png')
+
+
+@web.route('/favicon.ico')
+async def favicon_ico():
+    return await get_icon('favicon.ico', 'image/x-icon')
+
+
+@web.route('/favicon.svg')
+async def favicon_svg():
+    return await get_icon('favicon.svg', 'image/svg+xml')
+
+
+@web.route('/apple-touch-icon.png')
+async def apple_touch():
+    return await get_icon('apple-touch-icon.png')
+
+
+@web.route('/site.webmanifest')
+async def webmanifest():
+    return await get_icon('site.webmanifest', 'application/manifest+json')