Autocomplete in Shell

**Is your feature request related to a problem? Please describe.**
It is kind of inconvenient to completly write out every command, subcommand and option.

**Describe the solution you'd like**
At least the [Bash](https://www.gnu.org/software/bash/) does have a autocomplete feature, other shells should do too. There should be a Bash completion script or a more platform independent soulution to simplify the use of *booktrack-cli*.

**Describe alternatives you've considered**
None, yet.