* [system-dependencies] Add support for installing Xcode's first-launch installs.
* [system-dependencies] Use the Archive Utility to extract Xcode xips.
Apple changed their format (again), so don't try to process the xip manually,
just invoke Apple's Archive Utility.
Another advantage is that the Archive Utility compresses the output (to about
half), saving multiple GB of hard disk space (from ~10 GB to ~5 GB).
* [system-dependencies] Add Xcode testing comment.
* [system-dependencies] Check if an Xcode package is in ~/Downloads, and if so use it.
This makes it easier to verify that provisioning works correctly whenever a new Xcode comes out.
* [system-dependencies] Teach script about how to get the revision part of the mono version.
* Bump to mono 4.4 to get a 64-bit capable mono.
mdtool from Xamarin Studio 6.0 is a 64-bit process,
and thus requires a 64-bit capable system mono.
Rolf Bjarne Kvinge