add dao which takes care about all CRUD operations on storage
remove blockchain state since everything is stored on change
remove storage operations from structs(entities)
move structs to entities package
add processing of validators while block persist;
add validator structure with decoding/encoding;
add validator get from store;
add EnrollmentTX and StateTX processing;
add pubkey decode bytes, unique and contains functions;
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
* added account_state + changed ECPoint to PublicKey
* account state persist
* in depth test for existing accounts.
* implemented GetTransaction.
* added enrollment TX
* added persist of accounts and unspent coins
* bumped version -> 0.32.0
