Feature/enable creation of several features at once

[frwg]

Added additional functionality:

• The updateMultiple method now returns a Promise.
• The TableRenderer includes an addOrRefreshRow method that automatically handles whether a feature already exists in the table. This method is called after a successful updateMultiple AJAX call.
• A unique namespace ID is also generated for unsaved features to ensure they can be updated once the AJAX request successfully stores them.
• The oldGeometry attribute is set after a successful updateMultiple call.

These are non-breaking changes that should not affect the former processing of existing features being updated.