Drop wif.GetVerificationScript(), drop
smartcontract.CreateSignatureRedeemScript(), add GetVerificationScript()
directly to the PublicKey and use it everywhere.
This allows easier reuse of opcodes and in some cases allows to eliminate
dependencies on the whole vm package, like in compiler that only needs opcodes
and doesn't care about VM for any other purpose.
And yes, they're opcodes because an instruction is a whole thing with
operands, that's what context.Next() returns.
And drop associated _pkg.dev remnants (refs. #307).
Original `dev` branch had two separate packages for public and private keys,
but those are so intertwined (`TestHelper` subpackage is a proof) that it's
better unite them and all associated code (like WIF and NEP-2) in one
package. This patch also:
* creates internal `keytestcases` package to share things with wallet (maybe
it'll be changed in some future)
* ports some tests from `dev`
* ports Verify() method for public key from `dev`
* expands TestPrivateKey() with public key check
* deleted transfer_output added asset type and transaction result to core
* removed writing 0x00 when buffer length is 0
* Refactored emit into VM package + moved tx to own package.
* implemented transaction along with claimTransaction.
* refactored naming of transaction + added decode address for uint160 types
* removed unnecessary folder and files.
* transaction/smartcontract logic
* bumped version 0.24.0
* Initial draft of the neo-go wallet
* Cleanup + more test for util package
* integrated wallet into neo-cli partially
* base wallet implementation + smartcontract code.
