AELF V1.5.0
1.Multi-currency transaction fees support parallel
2.Support secondary delegate to pay transaction fees.
3.Support multiple tokens for threshold and free allowance
4.Optimise some system contracts to support virtual address
5.Add contract events, all logic that involves modifying balances fire corresponding events.
6.Optimise fees for token creation
7.Add VRF random number implementation to AEDPoS.
8.Support virtual addresses for creating tokens on the main chain and issuing NFTs on the side chains.