Move config dir on OSX

Hi,

Currently for OSX users config directory is located in ~/Library/Application Support/Cataclysm/.
I’m thinking of creating PR to move it to ~/.cataclysm-dda/ like for other non-windows/xdg builds.

It’s not much of a change but might introduce initial confusion for users.

As a MacOS user, I would expect graphical applications to behave according to the MacOS guidelines. In this case, writing to ~/Library/Application Support/Cataclysm

I think ~/Library/Application support/Cataclysm has some advantages and disadvantages, but in general is a good convention on OSX. And I think the pain of moving would be bigger than any potential benefits so I would leave it.
Other games like Minecraft use ~/Library/Application Support as well.

You can always make a softlink.