Stop reexporting the PAC under target

[jonas-schievink]

Builds on #171

Now we only have a single reexport of the PAC, called pac.

[Yatekii]

Is there a reasoning why it can't be called target anymore? I have neither preference but I'm curious. Also maybe we should include an alias to target still and add a deprecation message, such that it doesn't just explode for users.

[jonas-schievink]

Mainly because pac does the same thing as target but has a much clearer name. I'm planning to write a changelog so users can be informed of the change there. Since migrating is very mechanical we shouldn't need a migration period.

[Yatekii]

Ok, this is ok for me then :) I guess it's really much clearer :)