The logic here is that we'll have all binary encoding/decoding done via our io
package, which simplifies error handling. This functionality doesn't belong to
util, so it's moved.
This also expands BufBinWriter with Reset() method to fit the needs of core
package.
* Created test_data folder with block json files for testing + create separate file for block base.
* Fixed bug in WriteVarUint + Trim logic + unit tests
* Refactored store and add more tests for it.
* restore headerList from chain file
* Fix tx decode bug + lots of housekeeping.
* Implemented Node restore state from chain file.
* Created standalone package for storage. Added couple more methods to Batch and Store interfaces.
* Block persisting + tests
* bumped version -> 0.31.0
