Updates from the xpwn version

[andreas56]

Hi!

I noticed that the version of libdmg-hfsplus inside the xpwn project has some nice features that the version in the libdmg-hfsplus project is missing (I'm specially interested in the hfs decompression feature). I cherry-picked the three commits that contained libdmg-hfsplus changes from xpwn and merged them into a "from-xpwn" branch.

So this merge commit is a bit unusual as it doesn't contain any code that I wrote, it is just code from your own xpwn repo. Is there a reason the changes are not in the libdmg-hfsplus repo? Otherwise, feel free to merge this request.

[git-j]

thanks for the effort to create this request. +1 to merge +1 to explain the difference to the xpwn repo