Fixed lmdb concurrency issue
Added get method to lmdb (strict data grab without iterator)
Slight improvement to LMDB::value()
Added double reorg C++ unit test
Added DB transaction recycling and stricter read only DB transaction usage: shorter life span transactions allow reuse of space freed by write transactions.
Multi threaded block read for scan process -> 30~50% speed gain
Minor fix to dup height processing in LMDB wrapper