This is a quick first attempt at reading Xcode project files into
some sort of data structure.

You are hereby warned: The Xcode project file format is
undocumented, and is subject to change at any time, for any reason
that the Apple Developer Tools team may have. This code is mostly
automatically generated, so there are weirdnesses creeping around
inside.

I fully intend on improving the parsing (e.g. more specific types
for ordinary fields, rather than treating them all like NSString's),
so expect stuff to change.

All of this stuff is still copyright (C)2011 by David Brown. Don't
be a dick with the source code.