Replace alert() with modal for ACP password reset

Some browsers (e.g. Chrome) don't allow copying text out of alert()
dialogs.

www/js/acp.js

@@ -229,6 +229,20 @@ socket.on("acp-list-users", function (users) {
                     socket.emit("acp-reset-password", {
                         name: u.name,
                         email: u.email
+                    }, function (result) {
+                        if (result.error) {
+                            modalAlert({
+                                title: "Error",
+                                textContent: result.error
+                            });
+                        } else {
+                            var link = new URL("/account/passwordrecover/" + result.hash,
+                                    new URL(location));
+                            modalAlert({
+                                title: "Reset Link",
+                                textContent: link
+                            });
+                        }
                     });
                 }).appendTo(reset);
         }

www/js/util.js

@@ -2097,6 +2097,11 @@ function errDialog(err) {
  * I *promise* that one day I will actually split this file into submodules
  * -cal
  */
+
+/**
+ * modalAlert accepts options { title, textContent, htmlContent }
+ * All are optional
+ */
 function modalAlert(options) {
     if (typeof options !== "object" || options === null) {
         throw new Error("modalAlert() called without required parameter");