Merge branch 'LLNL-hydrogen'

* LLNL-hydrogen: (711 commits)
  Update README.md
  Add Clang 4.0 to .travis.yml and allow 6.0 to fail
  Fix ambiguous template special. errors with GCC 7+
  Add GCC 8 and Clang 6.0 to Travis CI.
  Enable OpenMP code only if EL_HYBRID is set
  CMake, GCC: Enable libquadmath detection for GCC 5.x to 8.x.
  Pass MPI_C_COMPILER instead of CMAKE_C_COMPILER to ensure that ParMetis is built with the right compiler (flags)
  Cleanup some issues with ETI and the Memory class (elemental#136)
  Distributed Cholesky for GPU (elemental#135)
  Debugging TranslateBetweenGrids (elemental#133)
  Fix an issue leading to bad linkage. (elemental#134)
  Update CMake support for CUDA HPC SDK and HIP (elemental#132)
  Update HydrogenConfig.cmake.in
  Update CMakeLists.txt
  Update CMakeLists.txt
  Add assertion that LAPACK is found. (elemental#131)
  Serial eigensolver for GPU (elemental#130)
  Remove FP16 from the ETI for eigensolvers. (elemental#129)
  Changed the CUDA compiler detection to just enable CUDA support rather (elemental#128)
  Reenable the HermitianEig API for sequential matrices. (elemental#127)
  ...

.gitignore

@@ -1,3 +1,16 @@
-build/
-*.swp
+# Emacs backup garbage
+.backup/
+
+# Other standard ignores
+*~
 *.pyc
+\#*#
+.#*
+.*.swp
+.DS_Store
+*.bak
+
+# building/install not-entirely-out-of-source stuff
+build*/
+install*/
+