Add device C-zeroing and remove blocking data transfers.

git-svn-id: svn://svn.code.sf.net/p/cp2k/code/trunk@14488 bac0169d-1eea-4375-b5f6-f89d2ced9994
Add debug options, cleanup code, and improve kernel performance.

git-svn-id: svn://svn.code.sf.net/p/cp2k/code/trunk@14489 bac0169d-1eea-4375-b5f6-f89d2ced9994