Make R extensable and add a couple of packages for verification.

Added R as a build system so that the create template will have the
correct configure line.
Added a regex for version parsing as the R URLs are a little odd.

lib/spack/spack/cmd/create.py

@@ -124,10 +124,12 @@ def __call__(self, stage):
         autotools = "configure('--prefix=%s' % prefix)"
         cmake     = "cmake('.', *std_cmake_args)"
         python    = "python('setup.py', 'install', '--prefix=%s' % prefix)"
+        r         = "R('CMD', 'INSTALL', '--library=%s' % self.module.r_lib_dir, '%s' % self.stage.archive_file)"
 
         config_lines = ((r'/configure$',      'autotools', autotools),
                         (r'/CMakeLists.txt$', 'cmake',     cmake),
-                        (r'/setup.py$',       'python',    python))
+                        (r'/setup.py$',       'python',    python),
+                        (r'/NAMESPACE$',      'r',         r))
 
         # Peek inside the tarball.
         tar = which('tar')
@@ -272,6 +274,10 @@ def create(parser, args):
     if guesser.build_system == 'python':
         name = 'py-%s' % name
 
+    # Prepend 'r-' to R package names, by convention.
+    if guesser.build_system == 'r':
+        name = 'r-%s' % name
+
     # Create a directory for the new package.
     pkg_path = repo.filename_for_package_name(name)
     if os.path.exists(pkg_path) and not args.force:

lib/spack/spack/url.py

@@ -206,6 +206,9 @@ def parse_version_offset(path):
         # e.g. lame-398-1
         (r'-((\d)+-\d)', stem),
 
+        # e.g. foobar_1.2-3
+        (r'_((\d+\.)+\d+(-\d+)?)', stem),
+
         # e.g. foobar-4.5.1
         (r'-((\d+\.)*\d+)$', stem),