v2.0.0-pre2: Second pre-release of TeleIRC v2.0.0

This commit marks the second release of the TeleIRC Go port. It is a
pre-release and does not yet have feature parity with the v1.x.x release
stream. USE THIS FOR TESTING ONLY!

Thanks and acknowledgements

This release was made possible to you by the TeleIRC core maintainers
and the project community:

• Justin W. Flory @jwflory
• Kennedy Kong @kennedy
• Kevin Assogba @10eMyrT
• Nicholas Jones @Zedjones
• Roman Nikitin @pomo-mondreganto
• Tim Zabel @Tjzabel

Thank you!

Changelog

Only covers changes from 2.0.0-pre1:

• New handlers:
  • Telegram Sticker handler
  • IRC blacklist handler
  • Add Telegram Photo handler
• Refactor/improve logging functionality
  • Add debug logging
• Increase unit test coverage from ~32% to 54%

New license

NOTE: TeleIRC is now licensed under the GPLv3 license. This is a
change from the MIT License. Current code and future contributions will
be licensed under the GPLv3.