* Lmdb internal objects reuse (built-in feature of lmdb):
- lmdb read transactions pool
- lmdb also support cursors reuse, but not implemented in this PR
And kv abstraction objects reuse:
- lmdbKV pool of all tx objects
- boltKV pool of all tx objects
- badgerKV pool of all tx objects
* switch makefile back to bolt
* switch makefile back to bolt
* lmdb test run
* switch makefile back to bolt
* cursors pool
* run lmdb tests
* make kv objects pool global
* switch makefile back to bolt
* remove badgers GOMAXPROC setup, because our app tunned for sequential read/writes, not for random throughput
* simplify code