Supporting logs and events properly

[axic]

For logs and errors need a way to define the shape of those, probably as a type:

data DepositEvent = DepositEvent(bytes32, uint256, memory(string));

emitLog(DepositEvent(...));

However somehow defining an instance (ABIEncodeable or LogEncodeable) on these would be needed without requiring the user to manually do these.

I think this could be accomplished with wrapping those in a Log type.

Also the question is whether to have syntactic sugar or not, ie solidity uses event DepositEvent(bytes32, uint256, memory(string));

Lastly, named parameters would be nice.