Allow adding multiple mods with one command

[maradotwebp]

Currently, ./pax add just enough resources adds a mod called just enough resources.

In the future, multiple mods should be able to be added through the ./pax add command, so:

• ./pax add just enough resources would install mods called just, enough and resources
• ./pax add 'just enough resources' would be needed to install a mod with spaces in its name.

This is a breaking change, tho, so v2.