Collected libxc issues
There are some problems/projects considering the libxc library that need to be tackled.
- Implement libxc functionals for the vaccuum region. This still misses the postprocessing of the potential (former issue #284 (closed)).
- The results for a calculation with our hard-coded GGAs and the corresponding libxc functionals differ. I was able to verify the MTs work fine; the problem is somewhere in the to- and from-transofrmation for the interstitial quantities (former issue #301 (closed)).
- The Diamond_SCAN test had always passed due to an internal error for god knows how long. It now fails properly and needs fixing.
- Implement a restart for MetaGGAs (see #298 (closed))