Move to Symfony Flex

The structure changed completely.
Bundles are gone. Everything is flatten in the folder `src`.
I separated import & api controllers to avoid _pollution_ in the main controller folder.

assets/themes/material/css/various.scss

@@ -0,0 +1,33 @@
+/* ==========================================================================
+ * Various
+ * ========================================================================== */
+
+div.settings div.file-field {
+  /* force height on non-input field in the settings page */
+  div,
+  ul {
+    margin-top: 40px;
+  }
+
+  /* but avoid to kill all file input */
+  div {
+    margin-top: inherit;
+  }
+}
+
+.input-field label.active {
+  font-size: 1rem;
+}
+
+nav .input-field input {
+  margin: 0;
+  padding-left: 0.5rem;
+}
+
+.tabs {
+  display: flex;
+}
+
+.tab {
+  flex: 1;
+}