added config manager (closes #18) and fixed crash at win

src/js/config.js

@@ -0,0 +1,76 @@
+const assets=require('assets');
+
+let watchers=Object.create(null);
+let lastWatchCode=1;
+
+const toBoolean=v => {
+	if(v=='false' || v==false) return false;
+	return true;
+};
+
+const get=key => {
+	let confVal=localStorage.getItem('config.'+key);
+	if(confVal===null) return assets.get('config')[key];
+	return confVal;
+};
+const getB=key => toBoolean(get(key));
+const getN=key => +get(key);
+const getS=key => ''+get(key);
+
+const set=(key, value) => {
+	localStorage.setItem('config.'+key, value);
+	let interested=watchers[key];
+	if(interested) interested.forEach(watcher => watcher(key, value));
+};
+
+const remove=key => {
+	localStorage.removeItem('config.'+key, value);
+	let interested=watchers[key];
+	if(interested) interested.forEach(watcher => watcher(key, assets.get('config')[key]));
+};
+const clear=() =>
+	Object
+		.keys(assets.get('config'))
+		.forEach(remove);
+
+const watch=(key, fn) => {
+	if(!watchers[key]) watchers[key]=[];
+	const code='w'+lastWatchCode++;
+	watchers[key][code]=fn;
+	return code;
+};
+const watchB=(key, fn) => watch(key, (k, v) => fn(k, toBoolean(v)));
+const watchN=(key, fn) => watch(key, (k, v) => fn(k, +v));
+const watchS=(key, fn) => watch(key, (k, v) => fn(k, ''+v));
+
+const unwatch=(key, code) => {
+	if(!watchers[key]) return;
+	delete watchers[key][code];
+};
+
+const list=() =>
+	Object
+		.keys(assets.get('config'));
+const dict=() => {
+	let dict=Object.create(null);
+	Object
+		.keys(assets.get('config'))
+		.forEach(
+			key => dict[key]={
+				raw: get(key),
+				b: getB(key),
+				n: getN(key),
+				s: getS(key)
+			}
+		);
+	return dict;
+};
+
+return module.exports={
+	get, getB, getN, getS,
+	set,
+	remove, clear,
+	watch, watchB, watchN, watchS,
+	unwatch,
+	list, dict
+};