Method to get an object from MetaChain by body-hash to get a specific version.

[streetycat]

I have not found a method to get an object from MetaChain by body-hash to get a specific version.

[lurenpluto]

This should be a function implemented by MetaChain's spv node, which needs to record the information of different body hash of the same object when scanning the main chain nodes and provide the corresponding query interface

See issue #108