Pybfbc2stats

This release adds error handling for "not found" errors returned by FESL on user lookups.

Other changes:
- Added keep alive option for underlying socket

This release addresses an issue with multiple clients sharing a common `completed_steps` dict.

This release improves the handling of all steps around initializing and shutting down the client/connection.

Changes/fixes:
- Log out automatically if client is used as context handler
- Validate login and raise exception if FESL returned an error
- Automatically respond to ping and memcheck (relevant mostly for long-running client instances)
- Fixed async client encountering errors if one client is shut down and another one is created

This release introduces user name search, which can find up to 50 users given a screen name (with trailing `*` wildcard).

This release addresses "Invalid FESL response" errors caused by the server sending packets of various different sizes.

This release introduces the option to use custom key sets for stats queries.