doc: add JSDoc annotations in the core folder

start documenting a bit, mostly inconsequential changes

core/form.js

@@ -1,3 +1,8 @@
+/**
+ * TODOC
+ * @param {*} encoded 
+ * @returns 
+ */
 function decode(encoded) {
 	let result = "";
 	for (let i = 0; i < encoded.length; i++) {
@@ -14,6 +19,12 @@ function decode(encoded) {
 	return result;
 }
 
+/**
+ * TODOC
+ * @param {*} encoded 
+ * @param {*} initial 
+ * @returns 
+ */
 function decodeForm(encoded, initial) {
 	let result = initial || {};
 	if (encoded) {