make helper function to extract filename from URL
update |makeURI| function

* early return for an invalid URL.
* delete unused |aDocument| parameter.
* use the public function |window.makeURI|.
arrange code about launch tools action for readability
use reliable |CustomEvent| constructor for user custom event
rewrite |promisePlacesDBResult| function with built-in module
get 'from visit' URL asynchronously

* Util.uc.js: remove unused function |getPlacesDBResult|.