Where we want to extend/override cosmos-sdk

[notatestuser]

1. drop GAS
2. drop BigInt
3. merge fronzen/locked coin onto the same account
4. logger to be async
5. Query Interface for CLI
6. Cache should not be cleared for checkState/DeliverState
7. overwrite transfer tx to make it support transferring tokens whose symbol begins with numbers like 1st, also we may add some precheck in it.
8. overwrite PersistentPreRunEFn, don't new Logger again.
9. change / drop the Bech32 readable address prefix
10. this is not about to change cosmos, but what we need to do if we fork cosmos.
    #155 In this pr, we agreed that we can do it in a better way if we forked cosmos. (extend sdk.Context with more functions)
11. BIP44Prefix is hardcoded to 118, https://github.com/cosmos/cosmos-sdk/blob/develop/crypto/keys/hd/hdpath.go#L28. we want to use our own number.