reduced int parsing to persistObj[n] in _restoreState function

Comment above _restoreState function suggests that persist object is something like: {'id1':'2','id3':'3','id2':'1'} where column indexes are strings. This causes error 'TypeError: b is undefined' because for 'id1' it concatenates string index '2' with 1 getting '21' which is parsed to 21 instead of 2+1=3 and so on... please apply this fix or change example persist object in comment above _restoreState to {'id1':2,'id3':3,'id2':1}