Various Slimming Changes

[ripytide]

Summary of changes:

• switched from custom logger to pretty_env_logger
• removed a bunch of outdated stuff like const MAJOR_UPDATE_MESSAGE since it will be easier to simply re-install from scratch given the amount of changes that have been made/will be made
• switched to the dirs library rather than rolling our own directory stuff with the path.rs file
• removed the errors.rs file since having both enum-based and string-based errors is confusing so now we just use anyhow string-based .context() errors.
• Deleted the old group-parsing code and replace with a todo!() since we are soon to attempt to replace it with a toml-based format.