New, cleaner package repository structure.

Package repositories now look like this:

    top-level-dir/
        repo.yaml
        packages/
            libelf/
                package.py
            mpich/
                package.py
            ...

This leaves room at the top level for additional metadata, source,
per-repo configs, indexes, etc., and it makes it easy to see that
something is a spack repo (just look for repo.yaml and packages).

var/spack/repos/builtin/packages/py-pyside/package.py

@@ -0,0 +1,45 @@
+from spack import *
+import os
+
+class PyPyside(Package):
+    """array processing for numbers, strings, records, and objects."""
+    homepage = "https://pypi.python.org/pypi/pyside"
+    url      = "https://pypi.python.org/packages/source/P/PySide/PySide-1.2.2.tar.gz"
+
+    version('1.2.2', 'c45bc400c8a86d6b35f34c29e379e44d')
+
+    # TODO: make build dependency
+    # depends_on("cmake")
+
+    extends('python')
+    depends_on('py-setuptools')
+    depends_on('qt@:4')
+
+    def patch(self):
+        """Undo PySide RPATH handling and add Spack RPATH."""
+        # Figure out the special RPATH
+        pypkg = self.spec['python'].package
+        rpath = self.rpath
+        rpath.append(os.path.join(self.prefix, pypkg.site_packages_dir, 'PySide'))
+
+        # Add Spack's standard CMake args to the sub-builds.
+        # They're called BY setup.py so we have to patch it.
+        filter_file(
+            r'OPTION_CMAKE,',
+            r'OPTION_CMAKE, ' + (
+                '"-DCMAKE_INSTALL_RPATH_USE_LINK_PATH=FALSE", '
+                '"-DCMAKE_INSTALL_RPATH=%s",' % ':'.join(rpath)),
+            'setup.py')
+
+        # PySide tries to patch ELF files to remove RPATHs
+        # Disable this and go with the one we set.
+        filter_file(
+            r'^\s*rpath_cmd\(pyside_path, srcpath\)',
+            r'#rpath_cmd(pyside_path, srcpath)',
+            'pyside_postinstall.py')
+
+
+    def install(self, spec, prefix):
+        python('setup.py', 'install',
+               '--prefix=%s' % prefix,
+               '--jobs=%s' % make_jobs)