maint: Remove core/remove and core/url.

Remove core/remove and core/url and it's usage in pat-slides.
core/url can nowadays be replaced by the URL interface from the web API.
core/remove did invoke the destroy event to invoke clean-up routines.

core/remove result in an infinite recursion error in combination with the
TinyMCE API due to core/remove's patching of the internal cleanData jQuery API.

pat-slides is currently not in a working state, so the removal is OK.
Anyways, this triggers the question how to handle Pattern cleanup in the
future. The answer is in a mutation observer on document level, but this
will be part of a future release.

Author: thet

src/core/remove.js

@@ -6,8 +6,6 @@
 import $ from "jquery";
 import registry from "../../core/registry";
 import utils from "../../core/utils";
-import url from "../../core/url";
-import "../../core/remove";
 
 var slides = {
     name: "slides",
@@ -24,9 +22,9 @@ var slides = {
         }
         await import("slides/src/slides"); // loads ``Presentation`` globally.
 
-        var parameters = url.parameters();
-        if (parameters.slides !== undefined) {
-            var requested_ids = slides._collapse_ids(parameters.slides);
+        const parameters = new URL(window.location.href).searchParams;
+        if (parameters.get("slides") !== null) {
+            var requested_ids = slides._collapse_ids(parameters.get("slides"));
             if (requested_ids) slides._remove_slides($el, requested_ids);
         }
         $el.each(function () {