* Added new config attributes: 'SecondsPerBlock','LowPriorityThreshold'
* Added new files:
* Added new method: CompareTo
* Fixed empty Slice case
* Added new methods: LessThan, GreaterThan, Equal, CompareTo
* Added new method: InputIntersection
* Added MaxTransactionSize, GroupOutputByAssetID
* Added ned method: ScriptHash
* Added new method: IsDoubleSpend
* Refactor blockchainer, Added Feer interface, Verify and GetMemPool method
* 1) Added MemPool
2) Added new methods to satisfy the blockchainer interface: IsLowPriority, Verify, GetMemPool
* Added new methods: RelayTxn, RelayDirectly
* Fixed tests
* Implemented RPC server method sendrawtransaction
* Refactor getrawtransaction, sendrawtransaction in separate methods
* Moved 'secondsPerBlock' to config file
* Implemented Kim suggestions:
1) Fixed data race issues
2) refactor Verify method
3) Get rid of unused InputIntersection method due to refactoring Verify method
4) Fixed bug in https://github.com/CityOfZion/neo-go/pull/174#discussion_r264108135
5) minor simplications of the code
* Fixed minor issues related to
1) space
2) getter methods do not need pointer on the receiver
3) error message
4) refactoring CompareTo method in uint256.go
* Fixed small issues
* Use sync.RWMutex instead of sync.Mutex
* Refined (R)Lock/(R)Unlock
* return error instead of bool in Verify methods
* VM:Add abstract stack item
* VM: Add stackItems; Array, Boolean, Int and ByteArray
* VM: Add tests for stack item
* VM: first pass at Random Access Stack object
* VM: Add Sub, Mul, Mod LSH, RSH
* VM: moved test helper functions into separate file
* VM: removed helper functions from stack_test.go
* Add conversions for bytearray and Int stack items
* Add instructions file for vm
* - Add guide to stack readme
- Add testReadInt64
* Add Builder
* Refactor Int, Boolean, ByteArray conversion
* Add Context stack Item
* Add Invocation stack - convenience RAS
* rename testhelper to test_helper
* Move opcode file
* - Add `Add` OpCode
- Add Opcode Function map
* - Add test for math `Add` opcode
- basic opcode execution
* Add popTwoIntegers convenience func
* Add `SUB` Opcode
* Export Context Read methods
- Return errors where failable
* - Add `Op` to handleOP func signature
- Add PushNBytes OPcode
* remove error on NewBoolean
- Expose underlying with Getter on Boolean StackItem
- Add Equals method for ByteArray
* Make Next() method on Context failable, refactor peekContext and Peek
* Add ExecuteOp, Step and Run methods on the VM
* Add Equal Opcode
* Add THROWIFNOT Opcode
* Add RET Opcode
* Refactor PushNBytes Opcode
* refactor Add, Sub to return VMSTATE
add popTwoByteArrays helper function
* Add basic tests for vm
* clarify vm states
* Add astack
* [VM]
Pass ResultStack to the opcode handlers
* [VM]
refactor handlers to have rstack as argument
* [Stack]
- Change RemoveCurrentContext for PopCurrentContext
- Add CopTo method to stack
* [VM]
Add Result stack Len check in simple run test
* [VM] fix typo
* [Peer/Stall]
Change seconds to milliseconds in test
