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/netlib-lapack/package.py

@@ -0,0 +1,59 @@
+from spack import *
+
+class NetlibLapack(Package):
+    """
+    LAPACK version 3.X is a comprehensive FORTRAN library that does
+    linear algebra operations including matrix inversions, least
+    squared solutions to linear sets of equations, eigenvector
+    analysis, singular value decomposition, etc. It is a very
+    comprehensive and reputable package that has found extensive
+    use in the scientific community.
+    """
+    homepage = "http://www.netlib.org/lapack/"
+    url      = "http://www.netlib.org/lapack/lapack-3.5.0.tgz"
+
+    version('3.5.0', 'b1d3e3e425b2e44a06760ff173104bdf')
+    version('3.4.2', '61bf1a8a4469d4bdb7604f5897179478')
+    version('3.4.1', '44c3869c38c8335c2b9c2a8bb276eb55')
+    version('3.4.0', '02d5706ec03ba885fc246e5fa10d8c70')
+    version('3.3.1', 'd0d533ec9a5b74933c2a1e84eedc58b4')
+
+    variant('shared', default=False, description="Build shared library version")
+
+    # virtual dependency
+    provides('lapack')
+
+    # blas is a virtual dependency.
+    depends_on('blas')
+
+    depends_on('cmake')
+
+    # Doesn't always build correctly in parallel
+    parallel = False
+
+    @when('^netlib-blas')
+    def get_blas_libs(self):
+        blas = self.spec['netlib-blas']
+        return [join_path(blas.prefix.lib, 'blas.a')]
+
+
+    @when('^atlas')
+    def get_blas_libs(self):
+        blas = self.spec['atlas']
+        return [join_path(blas.prefix.lib, l)
+                for l in ('libf77blas.a', 'libatlas.a')]
+
+
+    def install(self, spec, prefix):
+        blas_libs = ";".join(self.get_blas_libs())
+        cmake_args = [".", '-DBLAS_LIBRARIES=' + blas_libs]
+
+        if '+shared' in spec:
+            cmake_args.append('-DBUILD_SHARED_LIBS=ON')
+
+        cmake_args += std_cmake_args
+
+        cmake(*cmake_args)
+        make()
+        make("install")
+