Add Package : Zoltan

add modules package and have setup script find it if built

remove the part I added to setup-env.sh as this does not work unless the modules package is already built.

Add url_for_version function and gtk variant

add a path argument to the stage command

This version actually pulls the path through the package to deliver it
to each stage on creation when passed through the command.  This is
necessary due to the new StageComposite class that makes setting the
path directly on the stage impractical, it also takes the logic out of
package for the most part, which seems like an improvement.

Allow users to use spack to stage a, potentially complex, package into a
given path.  This is nice for packages with multiple resources that must
be placed, for example LLVM with all sub-projects.

+ libdrm depends_on libpciaccess.  Use spack provided libpciaccess.

Fixes install issues on OS/X for Quantum Espresso

VTK

Add CUDA and HOOMD-blue packages

oce: fix bugs related to NULL pointers and compiler optimisation

Needed for visit which depends on vtk@6.1.0~opengl2

Espresso uses unix utility `find dir -name \*.x` to determine the executable to
install. On OS/X, it also finds a bunch of debug symbols associated
with the exectuble. These files have the same name, but are in a
different directory. So the install process is done by hand in the
package.py file, for OS/X.

Rather than mess with the environment, have espresso install into the
right directory (prefix/bin).

- Modified arpack-ng to call libtoolize.

libpng depends on zlib.

doxygen: add missing dependencies

Provide new package numdiff

ninja: fix installation on OS X

Pkg graphviz

+ For darwin, add a dependency on gettext. This change was recommended in the discussion for PR#601.

docs: add a link to the spack repo in the PR section

mpich: disable fortran without a fortran compiler