Simplifies a lot of code and removes some duplication. Unfortunately I had to
move test_util random functions in same commit to avoid cycle
dependencies. One of these random functions was also used in core/transaction
testing, to simplify things I've just dropped it there and used a static
string (which is nice to have for a test anyway).
There is still sha256 left in wallet (but it needs to pass Hash structure into
the signing function).
* small fixes
* gofmt
* fix in raw tx build
* fixes after review
* balance getter interface
* moved address and signature calculation to public key
* errors handling
* PublicKey() returns PublicKey instead of bytes slice
* fixes after review
* fixes after review
* func to get private key from raw bytes
* added function to create raw transfer tx
* fixes
* more fixes
* prettify code and comments; neoscan interaction put in dedicated files
* 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.
