Some fixes:

1) long —> ssize_t for some classes.
2) Adds override keyword in js binding
3) fix for jsval_to_ssize and ssize_to_jsval, it only supports 32 bits now. Otherwise, (string).toFixed(0) will fails. Do we need 64 bit for JS?
4) Removes TableViewCell:: setObjectID and TableViewCell::getObjectID.