Cleaning lib

- Provides a more useful approach to directory switching, as suggested in #2412
- Deletes `aliases.zsh`, as almost all things defined in their can find a place in other files present
  - The directory aliases (some of the which duplicate functionality) are all in `directories.zsh`
  - The history alias is in `history.zsh`. Also refactored to a nicer case switch
  - Remaining pieces like the please alias for sudo are in `misc.zsh`
  - Moves a bindkey statement from `misc.zsh` to `key-bindings.zsh`
  - Deletes the .. aliases from common-aliases, they are in lib anyway
  - Avoids sourcing of autoenv with every call to cd. This plugin related code is also taken out of the lib directory. Its activation file is now sourced only once - if it's not present, the user is informed and the plugin disabled. Overriding cd by hand is not needed, autoenv does this by itself.

Closes #2412