- Update VT goroutines errs to avoid race condition
- Update pack & unpack siblings to use 2-byte for full length & bitmap
bytes length
- Add check in UnpackSiblings to avoid panic

- Update upFromNodes function for unbalanced tree case
- Add AddBatchTestVector2 & 3 with some edge cases
- Add checkRoots test method, which stores the Dump of the tree to file for after-debug