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/otf2/package.py

@@ -0,0 +1,74 @@
+# FIXME: Add copyright
+
+from spack import *
+from contextlib import closing
+import os
+
+class Otf2(Package):
+    """The Open Trace Format 2 is a highly scalable, memory efficient event
+       trace data format plus support library."""
+
+    homepage = "http://www.vi-hps.org/score-p"
+    url      = "http://www.vi-hps.org/upload/packages/otf2/otf2-1.4.tar.gz"
+
+    version('1.4',   'a23c42e936eb9209c4e08b61c3cf5092',
+            url="http://www.vi-hps.org/upload/packages/otf2/otf2-1.4.tar.gz")
+    version('1.3.1', 'd0ffc4e858455ace4f596f910e68c9f2',
+            url="http://www.vi-hps.org/upload/packages/otf2/otf2-1.3.1.tar.gz")
+    version('1.2.1', '8fb3e11fb7489896596ae2c7c83d7fc8',
+            url="http://www.vi-hps.org/upload/packages/otf2/otf2-1.2.1.tar.gz")
+
+    backend_user_provided = """\
+CC=cc
+CXX=c++
+F77=f77
+FC=f90
+CFLAGS=-fPIC
+CXXFLAGS=-fPIC
+"""
+    frontend_user_provided = """\
+CC_FOR_BUILD=cc
+CXX_FOR_BUILD=c++
+F77_FOR_BUILD=f70
+FC_FOR_BUILD=f90
+CFLAGS_FOR_BUILD=-fPIC
+CXXFLAGS_FOR_BUILD=-fPIC
+"""
+    mpi_user_provided = """\
+MPICC=cc
+MPICXX=c++
+MPIF77=f77
+MPIFC=f90
+MPI_CFLAGS=-fPIC
+MPI_CXXFLAGS=-fPIC
+"""
+
+    @when('@:1.2.1')
+    def version_specific_args(self):
+        return ["--with-platform=disabled", "CC=cc", "CXX=c++", "F77=f77", "F90=f90", "CFLAGS=-fPIC", "CXXFLAGS=-fPIC"]
+
+    @when('@1.3:')
+    def version_specific_args(self):
+        # TODO: figure out what scorep's build does as of otf2 1.3
+        return ["--with-custom-compilers"]
+
+    def install(self, spec, prefix):
+        # Use a custom compiler configuration, otherwise the score-p
+        # build system messes with spack's compiler settings.
+        # Create these three files in the build directory
+        with closing(open("platform-backend-user-provided", "w")) as backend_file:
+            backend_file.write(self.backend_user_provided)
+        with closing(open("platform-frontend-user-provided", "w")) as frontend_file:
+            frontend_file.write(self.frontend_user_provided)
+        with closing(open("platform-mpi-user-provided", "w")) as mpi_file:
+            mpi_file.write(self.mpi_user_provided)            
+
+        configure_args=["--prefix=%s" % prefix,
+                        "--enable-shared"]
+
+        configure_args.extend(self.version_specific_args())
+
+        configure(*configure_args)
+
+        make()
+        make("install")