Add dereference option

Hey @AvianFlu, this is the pull request for the "inflate symlinks" option I asked you about on IRC. Unix `cp` has a `--dereference` option, so I decided to call it "dereference" rather than "inflateSymlinks" to stick with the established terminology.

I also added tests for the default symlink handling while I was at it.

The first commit is mostly a massive re-indent; all the important stuff is in the second commit.