Delete unsuage less files and add rule to remove shadow in buttons if they are in a dropdown

less/modal.less

@@ -32,9 +32,9 @@
 }
 
 .hook-modal-misc() {
-  .uk-modal {
+  .uk-modal, uk-dropdown {
 
-    .uk-button {
+    .uk-button, uk-icon-button {
       box-shadow: none !important;
     }