Keyper Config.Unmarshal() seems broken

[RmbRT]

During my work on the TEE fortification of the keyper, I noticed there was no test for loading a TOML config. I wrote a test and it seems like somehow, the Viper object, while containing all the keys and values, is unable to properly transfer those into the Config object.

Calling .Unmarshal() on an empty Config object results in a segfault, because the keys are nil. If I GenerateKeys() and then call Unmarshal(), it does not panic, but all values seem to be left as 0's (default initialised), and the keys remain the same as when they were generated.

I wrote a test case for that in the TEE branch over at perun-network/shutter.