Fix Michelson instructions and add new ones

[m-kus]

Here are some changes made in order to comply with the latest language spec:

• DIP n <= optional nat argument comes first
• FAILWITH <= typo
• UNPACK additionally expects type argument
• CAST instruction also expects type argument (it's kinda deprecated, but still used in some tests)
• SUB_MUTEZ instruction added
• SELF and CONTRACT can have field annotation (entrypoint)
• set type argument is generalized to Type — while set, ticket, and map keys can only be comparable, current Michelson parser does not automatically converts comparable pairs, "or"s, and options into their "comparable twins", thus there can be an ambiguous situation.

[RomarQ]

Thanks for your contribution. The changes look good to me.

I noticed that this part of the code should contain more tests. Will add an issue to track it.