实现物体文件读取逻辑

Signed-off-by: Arathi <ssdfa7@gmail.com>
完善Object的读取(close #11)

现在会根据文件名判断物体类型
根据物体类型自行决定是否载入level和data_ptr (close #12)
现在ID以大端模式转换成int(fixed #13)

Signed-off-by: Arathi <ssdfa7@gmail.com>