Update HDF5 to 1.10.0

Add ipopt v3.12.4 package.

Add mpiseq headers to MUMPS installation (was: Add libexec dir to MUMPS installation)

Metis and suitesparse fixes

Added Environment Modules

Fixed TCL/Tk

[Needs Review] Fix conditional extends (BUG #683)

Added deprecation warning to netcdf-cxx

[WIP] py-pillow: Updated for variants

Added version 1.0 of sympy.

libxcb: Added comments on two dependencies Spack does not yet know ho…

git: added comment about newly discovered dependency

dbus: Added missing dependency (expat)

enhancement : recursive uninstallation of dependent packages

Fix #620, Resolve #664. Fix issues with build environment.

- Also added better regression tests for build environment.

the mpmath package. The py-mpmath package is added in this PR to
accommodate that.

Named "environment-modules" to be consistent with Fedora and Ubuntu repositories.

See d96ea5ba for original packages/modules/package.py

Add package for the nonlinear programming solver IPOPT. This
commit depends on the changes made in GitHub PR #711, since IPOPT
requires the headers that correspond to the fake MPI implementation
in sequential MUMPS.

Prior to this commit, spack installs a library called `libmpiseq` into
`spec['mumps'].prefix.lib` when it builds MUMPS without MPI. However, it
does not also install the headers corresponding to this library, so it
is impossible to compile source files that depend on function calls
implemented in this library. This commit fixes this problem by
installing these headers, which are needed by packages (e.g., IPOPT)
that depend on these headers.