BUGFIX: Compile w/out simulation interface

Fixed issue wherein compilation would fail when
BUILD_SIMULATION_INTERFACE was OFF. This is b/c
the master CMakeLists was always trying to link
the interface objects in to the cosmotools library.
This commit fixes this issue.
ENH: Add C interface to the build
ENH: Give files *.cxx extension for makefile build
ENH: Updates CMakelists to reflect file renames
ENH: Add build of tess to makefile build system
BUGFIX: Fix environment variable checking

Fixed issue wherein environment variable values were not being
correctly propagated to the Makefile.
BUGFIX: Compile w/out simulation interface

Fixed issue wherein compilation would fail when
BUILD_SIMULATION_INTERFACE was OFF. This is b/c
the master CMakeLists was always trying to link
the interface objects in to the cosmotools library.
This commit fixes this issue.

git-svn-id: https://svn.alcf.anl.gov/repos/DarkUniverse/hacc/trunk/cosmotools@1431 952bdfbe-fa2e-45c0-a9ae-ac90d4a62daf
ENH: Add C interface to the build

git-svn-id: https://svn.alcf.anl.gov/repos/DarkUniverse/hacc/trunk/cosmotools@1432 952bdfbe-fa2e-45c0-a9ae-ac90d4a62daf
ENH: Give files *.cxx extension for makefile build

git-svn-id: https://svn.alcf.anl.gov/repos/DarkUniverse/hacc/trunk/cosmotools@1433 952bdfbe-fa2e-45c0-a9ae-ac90d4a62daf
ENH: Updates CMakelists to reflect file renames

git-svn-id: https://svn.alcf.anl.gov/repos/DarkUniverse/hacc/trunk/cosmotools@1434 952bdfbe-fa2e-45c0-a9ae-ac90d4a62daf
ENH: Add build of tess to makefile build system

git-svn-id: https://svn.alcf.anl.gov/repos/DarkUniverse/hacc/trunk/cosmotools@1435 952bdfbe-fa2e-45c0-a9ae-ac90d4a62daf
BUGFIX: Fix environment variable checking

Fixed issue wherein environment variable values were not being
correctly propagated to the Makefile.

git-svn-id: https://svn.alcf.anl.gov/repos/DarkUniverse/hacc/trunk/cosmotools@1436 952bdfbe-fa2e-45c0-a9ae-ac90d4a62daf
Merge branch 'svn/makefile-build-updates'