Tasks for the command line interface

• assigned: pjotrp, artyom
• type: feature
• priority: high

• [ ] Provide sane CLI interface
• [ ] Add --map-size 10M switch
• [X] Use lmdb files instead of dir
• [ ] Find a way to open/create named DBs. Right now it's based on data.mdb renaming.
• [X] Move mgamma into ./bin
• [ ] Add ./bin/mgemma compatibility tool (note it is not mgamma)