Install multiple packages at once

- Append any selections to an array
- Pass that array to a single `pacman -U` invocation
- Required splitting prompt_to_install and testing separately
- Pull out main function for testability
Allow passing arbitrary pacman options after '--'

- Translations were updated (new usage), but not accurately.
Fix prompt to ignore

- Continue to do nothing if already present
- Append to first uncommented IgnorePkg entry, or
- Add a new entry after last commented IgnorePkg, or
- Add a new entry at the end of the file
Ensure non-empty man page in make target
Replace leading whitespace tests