Commit of changes to get things running with Xcode 5's clang compiler
on OS X 10.8. In particular, added a conditional macro to *not* call
realloc() in read_CPL_privatecode() and read_CPLcode_into_property ()
when using clang, since clang's implementation moves memory even when
downsizing. Other critical fixes included correcting the size of the
sortdatat to be memmoved in copy_elem(), and fixing a bug in
kill_edge_make_ring() where del_le() was called on a boundary that
wasn't initialized correctly.
Also added an Xcode project file, and removed extern.h in the top
level directory.