This PR introduces:
- db.put to put a value into the database
- db.get to read a value from the database
- db.delete to delete a value from the database
- db.stats to check compaction info from the database
- db.compact to trigger a db compaction
It also moves inspectdb to db.inspect.
# Conflicts:
# cmd/geth/chaincmd.go
# cmd/geth/main.go
# cmd/utils/flags.go
# core/rawdb/database.go
# ethdb/leveldb/leveldb.go