Allow multiple WoW paths

[mixedCase]

In Linux it's common to have different Wine prefixes for each game, specially when managed by a launcher like Lutris.

wowa currently assumes that both classic and retail folders must exist inside the same WoW directory, but this is not the case in this common scenario, it'd be nice to have support for it.

[inverimus]

I had this issue as well. I just created a symlink from my original classic install to where my retail folder actually is.