get BlockNode from database (#188)

* modify BlockNode to database

* modify newBlockNode

* optimise LoadBlockIndex

* optimise hash

* restruct blockIndex

* delete redundancy function

* remove blockIndex BlockExist function and add Remove cached blockNode

* modify function name

* modify blockwitness index

* optimise

* optimise chain best node

* modify dir

* optimise

* delete blockindex

* optimise style

* remove argument

* modify name

* modify get blockwitness func

* add getBestNode

* optimise blockHashes

* remove BlockNode

* optimise struct

* optimise

* optimise protocol

* optimise saveChainStatus

* optimise

* optimise

* remove consensusNodeManager

* modify node to blockheader

* modify node name

* remove redundancy getBlocker

* modify node to blockHeader

* add lock

* add deep copy

* fix

* modify function name

* modify order

* optimise init getBlockHashes

* optimise

* modify database test

* fix validation test

* fix txpool test

* fix utxo_view test

* delete protocol block test

* optimise name and position

* optimise

* delete cond

* modify Name

* abstract common function

* optimise

* add unit test

* optimise unit test

* delete code

* save main chain hash by height

* save main chain hashes

* fix error

* optimise

* optimise

* optimsie

* optimise

* optimise