Merge branch 'testing/cleanup' into 'master'

Cleanup testings/timing directories and prepare release

 * Remove testing directory
 * Remove timing directory
 * Remove plasma-conversion directory
 * Rename new-testing into testing directory, and binaries `new_Xtesting` become `chameleon_Xtesting`
 * Update release number, copyrights, date
 * Add testing helpers

See merge request solverstack/chameleon!197