doc: add JSDoc annotations in the core folder

start documenting a bit, mostly inconsequential changes

core/tfrpc.js

@@ -3,6 +3,10 @@ let g_api = {};
 let g_next_id = 1;
 let g_calls = {};
 
+/**
+ * TODOC
+ * @returns 
+ */
 function get_is_browser() {
 	try { return window !== undefined && console !== undefined; } catch { return false; }
 }
@@ -11,6 +15,13 @@ if (k_is_browser) {
 	print = console.log;
 }
 
+/**
+ * TODOC
+ * @param {*} target 
+ * @param {*} prop 
+ * @param {*} receiver 
+ * @returns 
+ */
 function make_rpc(target, prop, receiver) {
 	return function() {
 		let id = g_next_id++;
@@ -29,6 +40,10 @@ function make_rpc(target, prop, receiver) {
 	}
 }
 
+/**
+ * TODOC
+ * @param {*} response 
+ */
 function send(response) {
 	if (k_is_browser) {
 		window.parent.postMessage(response, '*');
@@ -37,6 +52,10 @@ function send(response) {
 	}
 }
 
+/**
+ * TODOC
+ * @param {*} message 
+ */
 function call_rpc(message) {
 	if (message && message.message === 'tfrpc') {
 		let id = message.id;
@@ -85,6 +104,10 @@ if (k_is_browser) {
 
 export let rpc = new Proxy({}, {get: make_rpc});
 
+/**
+ * TODOC
+ * @param {*} method 
+ */
 export function register(method) {
 	g_api[method.name] = method;
 }