Verification logic

[treyzania]

Currently the model I have in mind for doing verification logic is to have a structure representing a "valid state" of the network. After that you can call functions on it that "extend" the state and attempt to include the object (a block or something) into the history. It'll return a Result<ValiationState, (ValidationState, ValidationError)> for the

Since this isn't a settlement platform we don't need to have a highly-time-dependent system like Bitcoin or another cryptocurrency has, so there is some local malleability we can and should tolerate, but not in the long term.

This is absolutely necessary for having a daemon that can talk to other nodes working properly (#5).