Implement all logic on the client side in csvxmlV2.js

For completing the rewrite, translations and some UI work are still
needed.

See #14

public/assets/js/jszip/.editorconfig

@@ -0,0 +1,8 @@
+root = true
+
+[*]
+end_of_line = lf
+insert_final_newline = true
+charset = utf-8
+indent_style = space
+indent_size = 4