lmod : added support for the creation of hierarchical lua module files (#1723)

Includes :
- treatment of a generic hierarchy (i.e. lapack + mpi + compiler)
- possibility to specify which compilers are to be considered Core
- correct treatment of the 'family' directive
- unit tests for most new features

var/spack/repos/builtin/packages/llvm/package.py

@@ -22,9 +22,10 @@
 # License along with this program; if not, write to the Free Software
 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 ##############################################################################
-from spack import *
 import os
 
+from spack import *
+
 
 class Llvm(Package):
     """The LLVM Project is a collection of modular and reusable compiler and
@@ -37,9 +38,11 @@ class Llvm(Package):
     homepage = 'http://llvm.org/'
     url = 'http://llvm.org/releases/3.7.1/llvm-3.7.1.src.tar.xz'
 
+    family = 'compiler'  # Used by lmod
+
     # currently required by mesa package
     version('3.0', 'a8e5f5f1c1adebae7b4a654c376a6005',
-            url='http://llvm.org/releases/3.0/llvm-3.0.tar.gz')
+            url='http://llvm.org/releases/3.0/llvm-3.0.tar.gz')  # currently required by mesa package
 
     variant('debug', default=False,
             description="Build a debug version of LLVM, this increases "