make SC event log messages consistent

[Franziska-Mueller]

[qubicmio]

For users it would be great if the smart contract index and the message type (sub type within the log) would be easily accessible and always at the same position. For example in QX:

struct _TradeMessage
	{
		unsigned int _contractIndex;
		unsigned int _type;
		[...]
	} _tradeMessage;

But in other messages (for example qearn afaik) the type is not at the second position but at the end. Therefore these messages would need different deserialization from a client perspective.

Optional:

• Furthermore I think it would be nice if the contractIndex would be set fixed to the contract emitting the log message (theoretically another index could be set).
• From a user perspective it would be optimal if the smart contract index and the contracts internal type would be readable without looking into the message first. (Currently for QX I deserialize take the first part to determine the type and then deserialize the message a second time now knowing the type).

[J0ET0M]

actually the DummyContract*Message are already prepared and correct.
we should just enforce contracts to use this pattern.